diff --git a/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChart.java b/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChart.java
index 828669a892..cebe38b8f2 100644
--- a/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChart.java
+++ b/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChart.java
@@ -31,6 +31,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.function.Function;
+import java.util.function.Predicate;
 
 import javax.xml.namespace.QName;
 
@@ -115,8 +116,6 @@ public abstract class XDDFChart extends POIXMLDocumentPart implements TextContai
 
     private int chartIndex = 0;
 
-    private POIXMLDocumentPart documentPart = null;
-
     protected List<XDDFChartAxis> axes = new ArrayList<>();
 
     /**
@@ -362,14 +361,14 @@ public abstract class XDDFChart extends POIXMLDocumentPart implements TextContai
     }
 
     @Override
-    public <R> Optional<R> findDefinedParagraphProperty(Function<CTTextParagraphProperties, Boolean> isSet,
+    public <R> Optional<R> findDefinedParagraphProperty(Predicate<CTTextParagraphProperties> isSet,
         Function<CTTextParagraphProperties, R> getter) {
         // TODO Auto-generated method stub
         return Optional.empty();
     }
 
     @Override
-    public <R> Optional<R> findDefinedRunProperty(Function<CTTextCharacterProperties, Boolean> isSet,
+    public <R> Optional<R> findDefinedRunProperty(Predicate<CTTextCharacterProperties> isSet,
         Function<CTTextCharacterProperties, R> getter) {
         // TODO Auto-generated method stub
         return Optional.empty();
@@ -578,23 +577,23 @@ public abstract class XDDFChart extends POIXMLDocumentPart implements TextContai
     private Map<Long, XDDFChartAxis> getCategoryAxes() {
         CTPlotArea plotArea = getCTPlotArea();
         int sizeOfArray = plotArea.sizeOfCatAxArray();
-        Map<Long, XDDFChartAxis> axes = new HashMap<>(sizeOfArray);
+        Map<Long, XDDFChartAxis> axesMap = new HashMap<>(sizeOfArray);
         for (int i = 0; i < sizeOfArray; i++) {
             CTCatAx category = plotArea.getCatAxArray(i);
-            axes.put(category.getAxId().getVal(), new XDDFCategoryAxis(category));
+            axesMap.put(category.getAxId().getVal(), new XDDFCategoryAxis(category));
         }
-        return axes;
+        return axesMap;
     }
 
     private Map<Long, XDDFValueAxis> getValueAxes() {
         CTPlotArea plotArea = getCTPlotArea();
         int sizeOfArray = plotArea.sizeOfValAxArray();
-        Map<Long, XDDFValueAxis> axes = new HashMap<>(sizeOfArray);
+        Map<Long, XDDFValueAxis> axesMap = new HashMap<>(sizeOfArray);
         for (int i = 0; i < sizeOfArray; i++) {
             CTValAx values = plotArea.getValAxArray(i);
-            axes.put(values.getAxId().getVal(), new XDDFValueAxis(values));
+            axesMap.put(values.getAxId().getVal(), new XDDFValueAxis(values));
         }
-        return axes;
+        return axesMap;
     }
 
     public XDDFValueAxis createValueAxis(AxisPosition pos) {
@@ -767,15 +766,14 @@ public abstract class XDDFChart extends POIXMLDocumentPart implements TextContai
      */
     public PackageRelationship createRelationshipInChart(POIXMLRelation chartRelation, POIXMLFactory chartFactory,
         int chartIndex) {
-        documentPart = createRelationship(chartRelation, chartFactory, chartIndex, true).getDocumentPart();
+        POIXMLDocumentPart documentPart =
+                createRelationship(chartRelation, chartFactory, chartIndex, true).getDocumentPart();
         return addRelation(null, chartRelation, documentPart).getRelationship();
     }
 
     /**
      * if embedded part was null then create new part
      *
-     * @param chartRelation
-     *            chart relation object
      * @param chartWorkbookRelation
      *            chart workbook relation object
      * @param chartFactory
@@ -784,8 +782,8 @@ public abstract class XDDFChart extends POIXMLDocumentPart implements TextContai
      * @throws InvalidFormatException
      * @since POI 4.0.0
      */
-    private PackagePart createWorksheetPart(POIXMLRelation chartRelation, POIXMLRelation chartWorkbookRelation,
-        POIXMLFactory chartFactory) throws InvalidFormatException {
+    private PackagePart createWorksheetPart(POIXMLRelation chartWorkbookRelation, POIXMLFactory chartFactory)
+            throws InvalidFormatException {
         PackageRelationship xlsx = createRelationshipInChart(chartWorkbookRelation, chartFactory, chartIndex);
         setExternalId(xlsx.getId());
         return getTargetPart(xlsx);
@@ -803,11 +801,10 @@ public abstract class XDDFChart extends POIXMLDocumentPart implements TextContai
     public void saveWorkbook(XSSFWorkbook workbook) throws IOException, InvalidFormatException {
         PackagePart worksheetPart = getWorksheetPart();
         if (worksheetPart == null) {
-            POIXMLRelation chartRelation = getChartRelation();
             POIXMLRelation chartWorkbookRelation = getChartWorkbookRelation();
             POIXMLFactory chartFactory = getChartFactory();
-            if (chartRelation != null && chartWorkbookRelation != null && chartFactory != null) {
-                worksheetPart = createWorksheetPart(chartRelation, chartWorkbookRelation, chartFactory);
+            if (chartWorkbookRelation != null && chartFactory != null) {
+                worksheetPart = createWorksheetPart(chartWorkbookRelation, chartFactory);
             } else {
                 throw new InvalidFormatException("unable to determine chart relations");
             }
@@ -950,6 +947,9 @@ public abstract class XDDFChart extends POIXMLDocumentPart implements TextContai
      */
     public CellReference setSheetTitle(String title, int column) {
         XSSFSheet sheet = getSheet();
+        if (sheet == null) {
+            return null;
+        }
         XSSFRow row = getRow(sheet, 0);
         XSSFCell cell = getCell(row, column);
         cell.setCellValue(title);
@@ -1000,7 +1000,7 @@ public abstract class XDDFChart extends POIXMLDocumentPart implements TextContai
         return null;
     }
 
-    private void setWorksheetPartCommitted() throws InvalidFormatException {
+    private void setWorksheetPartCommitted() {
         for (RelationPart part : getRelationParts()) {
             if (POIXMLDocument.PACK_OBJECT_REL_TYPE.equals(part.getRelationship().getRelationshipType())) {
                 part.getDocumentPart().setCommitted(true);
diff --git a/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChartAxis.java b/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChartAxis.java
index d0a8e61d4b..c04e066ed2 100644
--- a/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChartAxis.java
+++ b/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChartAxis.java
@@ -408,7 +408,10 @@ public abstract class XDDFChartAxis implements HasShapeProperties {
     }
 
     protected long getNextAxId(CTPlotArea plotArea) {
-        long totalAxisCount = plotArea.sizeOfValAxArray() + plotArea.sizeOfCatAxArray() + plotArea.sizeOfDateAxArray()
+        long totalAxisCount = 0L
+                + plotArea.sizeOfValAxArray()
+                + plotArea.sizeOfCatAxArray()
+                + plotArea.sizeOfDateAxArray()
                 + plotArea.sizeOfSerAxArray();
         return totalAxisCount;
     }
diff --git a/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChartLegend.java b/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChartLegend.java
index 003e613e22..d7a77f568b 100644
--- a/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChartLegend.java
+++ b/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFChartLegend.java
@@ -20,6 +20,7 @@ package org.apache.poi.xddf.usermodel.chart;
 import java.util.List;
 import java.util.Optional;
 import java.util.function.Function;
+import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
 import org.apache.poi.util.Beta;
@@ -195,14 +196,16 @@ public final class XDDFChartLegend implements TextContainer {
         legend.getOverlay().setVal(value);
     }
 
+    @Override
     public <R> Optional<R> findDefinedParagraphProperty(
-            Function<CTTextParagraphProperties, Boolean> isSet,
+            Predicate<CTTextParagraphProperties> isSet,
             Function<CTTextParagraphProperties, R> getter) {
         return Optional.empty(); // chart legend has no (indirect) paragraph properties
     }
 
+    @Override
     public <R> Optional<R> findDefinedRunProperty(
-            Function<CTTextCharacterProperties, Boolean> isSet,
+            Predicate<CTTextCharacterProperties> isSet,
             Function<CTTextCharacterProperties, R> getter) {
         return Optional.empty(); // chart legend has no (indirect) paragraph properties
     }
diff --git a/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFLegendEntry.java b/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFLegendEntry.java
index 6668e77235..526c1ebf19 100644
--- a/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFLegendEntry.java
+++ b/src/ooxml/java/org/apache/poi/xddf/usermodel/chart/XDDFLegendEntry.java
@@ -19,6 +19,7 @@ package org.apache.poi.xddf.usermodel.chart;
 
 import java.util.Optional;
 import java.util.function.Function;
+import java.util.function.Predicate;
 
 import org.apache.poi.util.Beta;
 import org.apache.poi.util.Internal;
@@ -113,14 +114,14 @@ public class XDDFLegendEntry implements TextContainer {
 
     @Override
     public <R> Optional<R> findDefinedParagraphProperty(
-            Function<CTTextParagraphProperties, Boolean> isSet,
+            Predicate<CTTextParagraphProperties> isSet,
             Function<CTTextParagraphProperties, R> getter) {
         return Optional.empty(); // legend entry has no (indirect) paragraph properties
     }
 
     @Override
     public <R> Optional<R> findDefinedRunProperty(
-            Function<CTTextCharacterProperties, Boolean> isSet,
+            Predicate<CTTextCharacterProperties> isSet,
             Function<CTTextCharacterProperties, R> getter) {
         return Optional.empty(); // legend entry has no (indirect) paragraph properties
     }
diff --git a/src/ooxml/java/org/apache/poi/xddf/usermodel/text/TextContainer.java b/src/ooxml/java/org/apache/poi/xddf/usermodel/text/TextContainer.java
index 9e11d21e03..a8c89d02f5 100644
--- a/src/ooxml/java/org/apache/poi/xddf/usermodel/text/TextContainer.java
+++ b/src/ooxml/java/org/apache/poi/xddf/usermodel/text/TextContainer.java
@@ -19,6 +19,7 @@ package org.apache.poi.xddf.usermodel.text;
 
 import java.util.Optional;
 import java.util.function.Function;
+import java.util.function.Predicate;
 
 import org.apache.poi.util.Beta;
 import org.openxmlformats.schemas.drawingml.x2006.main.CTTextCharacterProperties;
@@ -27,10 +28,10 @@ import org.openxmlformats.schemas.drawingml.x2006.main.CTTextParagraphProperties
 @Beta
 public interface TextContainer {
 
-    <R> Optional<R> findDefinedParagraphProperty(Function<CTTextParagraphProperties, Boolean> isSet,
+    <R> Optional<R> findDefinedParagraphProperty(Predicate<CTTextParagraphProperties> isSet,
         Function<CTTextParagraphProperties, R> getter);
 
-    <R> Optional<R> findDefinedRunProperty(Function<CTTextCharacterProperties, Boolean> isSet,
+    <R> Optional<R> findDefinedRunProperty(Predicate<CTTextCharacterProperties> isSet,
         Function<CTTextCharacterProperties, R> getter);
 
 }
diff --git a/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextBody.java b/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextBody.java
index 6eae7b88c2..2c97837ab2 100644
--- a/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextBody.java
+++ b/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextBody.java
@@ -22,6 +22,7 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Optional;
 import java.util.function.Function;
+import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
 import org.apache.poi.util.Beta;
@@ -337,12 +338,12 @@ public class XDDFTextBody {
     }
 
     @Internal
-    protected <R> Optional<R> findDefinedParagraphProperty(Function<CTTextParagraphProperties, Boolean> isSet,
+    protected <R> Optional<R> findDefinedParagraphProperty(Predicate<CTTextParagraphProperties> isSet,
         Function<CTTextParagraphProperties, R> getter, int level) {
         if (_body.isSetLstStyle() && level >= 0) {
             CTTextListStyle list = _body.getLstStyle();
             CTTextParagraphProperties props = level == 0 ? list.getDefPPr() : retrieveProperties(list, level);
-            if (props != null && isSet.apply(props)) {
+            if (props != null && isSet.test(props)) {
                 return Optional.of(getter.apply(props));
             } else {
                 return findDefinedParagraphProperty(isSet, getter, level - 1);
@@ -355,12 +356,12 @@ public class XDDFTextBody {
     }
 
     @Internal
-    protected <R> Optional<R> findDefinedRunProperty(Function<CTTextCharacterProperties, Boolean> isSet,
+    protected <R> Optional<R> findDefinedRunProperty(Predicate<CTTextCharacterProperties> isSet,
         Function<CTTextCharacterProperties, R> getter, int level) {
         if (_body.isSetLstStyle() && level >= 0) {
             CTTextListStyle list = _body.getLstStyle();
             CTTextParagraphProperties props = level == 0 ? list.getDefPPr() : retrieveProperties(list, level);
-            if (props != null && props.isSetDefRPr() && isSet.apply(props.getDefRPr())) {
+            if (props != null && props.isSetDefRPr() && isSet.test(props.getDefRPr())) {
                 return Optional.of(getter.apply(props.getDefRPr()));
             } else {
                 return findDefinedRunProperty(isSet, getter, level - 1);
diff --git a/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextParagraph.java b/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextParagraph.java
index f2a2107edd..97082725c1 100644
--- a/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextParagraph.java
+++ b/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextParagraph.java
@@ -23,6 +23,7 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Optional;
 import java.util.function.Function;
+import java.util.function.Predicate;
 
 import org.apache.commons.collections4.iterators.IteratorIterable;
 import org.apache.commons.collections4.iterators.ReverseListIterator;
@@ -178,8 +179,10 @@ public class XDDFTextParagraph {
      * @return alignment that is applied to the paragraph
      */
     public TextAlignment getTextAlignment() {
-        return findDefinedParagraphProperty(props -> props.isSetAlgn(), props -> props.getAlgn())
-            .map(align -> TextAlignment.valueOf(align)).orElse(null);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetAlgn,
+                CTTextParagraphProperties::getAlgn)
+            .map(TextAlignment::valueOf).orElse(null);
     }
 
     /**
@@ -205,8 +208,10 @@ public class XDDFTextParagraph {
      * @return alignment that is applied to the paragraph
      */
     public FontAlignment getFontAlignment() {
-        return findDefinedParagraphProperty(props -> props.isSetFontAlgn(), props -> props.getFontAlgn())
-            .map(align -> FontAlignment.valueOf(align)).orElse(null);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetFontAlgn,
+                CTTextParagraphProperties::getFontAlgn)
+            .map(FontAlignment::valueOf).orElse(null);
     }
 
     /**
@@ -230,8 +235,10 @@ public class XDDFTextParagraph {
      *         the paragraph.
      */
     public Double getIndentation() {
-        return findDefinedParagraphProperty(props -> props.isSetIndent(), props -> props.getIndent())
-            .map(emu -> Units.toPoints(emu)).orElse(null);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetIndent,
+                CTTextParagraphProperties::getIndent)
+            .map(Units::toPoints).orElse(null);
     }
 
     /**
@@ -259,8 +266,10 @@ public class XDDFTextParagraph {
      * @return the left margin, in points, of the paragraph.
      */
     public Double getMarginLeft() {
-        return findDefinedParagraphProperty(props -> props.isSetMarL(), props -> props.getMarL())
-            .map(emu -> Units.toPoints(emu)).orElse(null);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetMarL,
+                CTTextParagraphProperties::getMarL)
+            .map(Units::toPoints).orElse(null);
     }
 
     /**
@@ -290,8 +299,10 @@ public class XDDFTextParagraph {
      * @return the right margin, in points, of the paragraph.
      */
     public Double getMarginRight() {
-        return findDefinedParagraphProperty(props -> props.isSetMarR(), props -> props.getMarR())
-            .map(emu -> Units.toPoints(emu)).orElse(null);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetMarR,
+                CTTextParagraphProperties::getMarR)
+            .map(Units::toPoints).orElse(null);
     }
 
     /**
@@ -322,8 +333,10 @@ public class XDDFTextParagraph {
      *         points.
      */
     public Double getDefaultTabSize() {
-        return findDefinedParagraphProperty(props -> props.isSetDefTabSz(), props -> props.getDefTabSz())
-            .map(emu -> Units.toPoints(emu)).orElse(null);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetDefTabSz,
+                CTTextParagraphProperties::getDefTabSz)
+            .map(Units::toPoints).orElse(null);
     }
 
     /**
@@ -352,8 +365,10 @@ public class XDDFTextParagraph {
      * @return the vertical line spacing.
      */
     public XDDFSpacing getLineSpacing() {
-        return findDefinedParagraphProperty(props -> props.isSetLnSpc(), props -> props.getLnSpc())
-            .map(spacing -> extractSpacing(spacing)).orElse(null);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetLnSpc,
+                CTTextParagraphProperties::getLnSpc)
+            .map(this::extractSpacing).orElse(null);
 
     }
 
@@ -403,8 +418,10 @@ public class XDDFTextParagraph {
      * @return the vertical white space before the paragraph.
      */
     public XDDFSpacing getSpaceBefore() {
-        return findDefinedParagraphProperty(props -> props.isSetSpcBef(), props -> props.getSpcBef())
-            .map(spacing -> extractSpacing(spacing)).orElse(null);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetSpcBef,
+                CTTextParagraphProperties::getSpcBef)
+            .map(this::extractSpacing).orElse(null);
     }
 
     /**
@@ -451,8 +468,10 @@ public class XDDFTextParagraph {
      * @return the vertical white space after the paragraph.
      */
     public XDDFSpacing getSpaceAfter() {
-        return findDefinedParagraphProperty(props -> props.isSetSpcAft(), props -> props.getSpcAft())
-            .map(spacing -> extractSpacing(spacing)).orElse(null);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetSpcAft,
+                CTTextParagraphProperties::getSpcAft)
+            .map(this::extractSpacing).orElse(null);
     }
 
     /**
@@ -599,7 +618,10 @@ public class XDDFTextParagraph {
     }
 
     public boolean hasEastAsianLineBreak() {
-        return findDefinedParagraphProperty(props -> props.isSetEaLnBrk(), props -> props.getEaLnBrk()).orElse(false);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetEaLnBrk,
+                CTTextParagraphProperties::getEaLnBrk)
+            .orElse(false);
     }
 
     public void setEastAsianLineBreak(Boolean value) {
@@ -609,7 +631,9 @@ public class XDDFTextParagraph {
     }
 
     public boolean hasLatinLineBreak() {
-        return findDefinedParagraphProperty(props -> props.isSetLatinLnBrk(), props -> props.getLatinLnBrk())
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetLatinLnBrk,
+                CTTextParagraphProperties::getLatinLnBrk)
             .orElse(false);
     }
 
@@ -620,7 +644,9 @@ public class XDDFTextParagraph {
     }
 
     public boolean hasHangingPunctuation() {
-        return findDefinedParagraphProperty(props -> props.isSetHangingPunct(), props -> props.getHangingPunct())
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetHangingPunct,
+                CTTextParagraphProperties::getHangingPunct)
             .orElse(false);
     }
 
@@ -631,7 +657,10 @@ public class XDDFTextParagraph {
     }
 
     public boolean isRightToLeft() {
-        return findDefinedParagraphProperty(props -> props.isSetRtl(), props -> props.getRtl()).orElse(false);
+        return findDefinedParagraphProperty(
+                CTTextParagraphProperties::isSetRtl,
+                CTTextParagraphProperties::getRtl)
+            .orElse(false);
     }
 
     public void setRightToLeft(Boolean value) {
@@ -760,7 +789,7 @@ public class XDDFTextParagraph {
         return getProperties();
     }
 
-    protected <R> Optional<R> findDefinedParagraphProperty(Function<CTTextParagraphProperties, Boolean> isSet,
+    protected <R> Optional<R> findDefinedParagraphProperty(Predicate<CTTextParagraphProperties> isSet,
         Function<CTTextParagraphProperties, R> getter) {
         if (_p.isSetPPr()) {
             int level = _p.getPPr().isSetLvl() ? 1 + _p.getPPr().getLvl() : 0;
@@ -770,17 +799,17 @@ public class XDDFTextParagraph {
         }
     }
 
-    private <R> Optional<R> findDefinedParagraphProperty(Function<CTTextParagraphProperties, Boolean> isSet,
+    private <R> Optional<R> findDefinedParagraphProperty(Predicate<CTTextParagraphProperties> isSet,
         Function<CTTextParagraphProperties, R> getter, int level) {
         final CTTextParagraphProperties props = _p.getPPr();
-        if (props != null && isSet.apply(props)) {
+        if (props != null && isSet.test(props)) {
             return Optional.ofNullable(getter.apply(props));
         } else {
             return _parent.findDefinedParagraphProperty(isSet, getter, level);
         }
     }
 
-    protected <R> Optional<R> findDefinedRunProperty(Function<CTTextCharacterProperties, Boolean> isSet,
+    protected <R> Optional<R> findDefinedRunProperty(Predicate<CTTextCharacterProperties> isSet,
         Function<CTTextCharacterProperties, R> getter) {
         if (_p.isSetPPr()) {
             int level = _p.getPPr().isSetLvl() ? 1 + _p.getPPr().getLvl() : 0;
@@ -790,10 +819,10 @@ public class XDDFTextParagraph {
         }
     }
 
-    private <R> Optional<R> findDefinedRunProperty(Function<CTTextCharacterProperties, Boolean> isSet,
+    private <R> Optional<R> findDefinedRunProperty(Predicate<CTTextCharacterProperties> isSet,
         Function<CTTextCharacterProperties, R> getter, int level) {
         final CTTextCharacterProperties props = _p.getPPr().isSetDefRPr() ? _p.getPPr().getDefRPr() : null;
-        if (props != null && isSet.apply(props)) {
+        if (props != null && isSet.test(props)) {
             return Optional.ofNullable(getter.apply(props));
         } else {
             return _parent.findDefinedRunProperty(isSet, getter, level);
diff --git a/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextRun.java b/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextRun.java
index 8d2c5c2015..a9583c200d 100644
--- a/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextRun.java
+++ b/src/ooxml/java/org/apache/poi/xddf/usermodel/text/XDDFTextRun.java
@@ -21,6 +21,7 @@ import java.util.LinkedList;
 import java.util.Locale;
 import java.util.Optional;
 import java.util.function.Function;
+import java.util.function.Predicate;
 
 import org.apache.poi.common.usermodel.fonts.FontGroup;
 import org.apache.poi.ooxml.POIXMLRelation;
@@ -108,7 +109,9 @@ public class XDDFTextRun {
     }
 
     public Boolean getDirty() {
-        return findDefinedProperty(props -> props.isSetDirty(), props -> props.getDirty())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetDirty,
+                CTTextCharacterProperties::getDirty)
             .orElse(null);
     }
 
@@ -117,7 +120,9 @@ public class XDDFTextRun {
     }
 
     public Boolean getSpellError() {
-        return findDefinedProperty(props -> props.isSetErr(), props -> props.getErr())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetErr,
+                CTTextCharacterProperties::getErr)
             .orElse(null);
     }
 
@@ -126,7 +131,9 @@ public class XDDFTextRun {
     }
 
     public Boolean getNoProof() {
-        return findDefinedProperty(props -> props.isSetNoProof(), props -> props.getNoProof())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetNoProof,
+                CTTextCharacterProperties::getNoProof)
             .orElse(null);
     }
 
@@ -135,7 +142,9 @@ public class XDDFTextRun {
     }
 
     public Boolean getNormalizeHeights() {
-        return findDefinedProperty(props -> props.isSetNormalizeH(), props -> props.getNormalizeH())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetNormalizeH,
+                CTTextCharacterProperties::getNormalizeH)
             .orElse(null);
     }
 
@@ -144,7 +153,9 @@ public class XDDFTextRun {
     }
 
     public boolean isKumimoji() {
-        return findDefinedProperty(props -> props.isSetKumimoji(), props -> props.getKumimoji())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetKumimoji,
+                CTTextCharacterProperties::getKumimoji)
             .orElse(false);
     }
 
@@ -162,7 +173,9 @@ public class XDDFTextRun {
      * @return whether this run of text is formatted as bold text.
      */
     public boolean isBold() {
-        return findDefinedProperty(props -> props.isSetB(), props -> props.getB())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetB,
+                CTTextCharacterProperties::getB)
             .orElse(false);
     }
 
@@ -178,7 +191,9 @@ public class XDDFTextRun {
      * @return whether this run of text is formatted as italic text.
      */
     public boolean isItalic() {
-        return findDefinedProperty(props -> props.isSetI(), props -> props.getI())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetI,
+                CTTextCharacterProperties::getI)
             .orElse(false);
     }
 
@@ -194,7 +209,9 @@ public class XDDFTextRun {
      * @return whether this run of text is formatted as striked text.
      */
     public boolean isStrikeThrough() {
-        return findDefinedProperty(props -> props.isSetStrike(), props -> props.getStrike())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetStrike,
+                CTTextCharacterProperties::getStrike)
             .map(strike -> strike != STTextStrikeType.NO_STRIKE)
             .orElse(false);
     }
@@ -203,8 +220,10 @@ public class XDDFTextRun {
      * @return which strike style this run of text is formatted with.
      */
     public StrikeType getStrikeThrough() {
-        return findDefinedProperty(props -> props.isSetStrike(), props -> props.getStrike())
-            .map(strike -> StrikeType.valueOf(strike))
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetStrike,
+                CTTextCharacterProperties::getStrike)
+            .map(StrikeType::valueOf)
             .orElse(null);
     }
 
@@ -220,7 +239,9 @@ public class XDDFTextRun {
      * @return whether this run of text is formatted as underlined text.
      */
     public boolean isUnderline() {
-        return findDefinedProperty(props -> props.isSetU(), props -> props.getU())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetU,
+                CTTextCharacterProperties::getU)
             .map(underline -> underline != STTextUnderlineType.NONE)
             .orElse(false);
     }
@@ -229,8 +250,10 @@ public class XDDFTextRun {
      * @return which underline style this run of text is formatted with.
      */
     public UnderlineType getUnderline() {
-        return findDefinedProperty(props -> props.isSetU(), props -> props.getU())
-            .map(underline -> UnderlineType.valueOf(underline))
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetU,
+                CTTextCharacterProperties::getU)
+            .map(UnderlineType::valueOf)
             .orElse(null);
     }
 
@@ -246,7 +269,9 @@ public class XDDFTextRun {
      * @return whether this run of text is formatted as capitalized text.
      */
     public boolean isCapitals() {
-        return findDefinedProperty(props -> props.isSetCap(), props -> props.getCap())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetCap,
+                CTTextCharacterProperties::getCap)
             .map(caps -> caps != STTextCapsType.NONE)
             .orElse(false);
     }
@@ -255,8 +280,10 @@ public class XDDFTextRun {
      * @return which caps style this run of text is formatted with.
      */
     public CapsType getCapitals() {
-        return findDefinedProperty(props -> props.isSetCap(), props -> props.getCap())
-            .map(caps -> CapsType.valueOf(caps))
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetCap,
+                CTTextCharacterProperties::getCap)
+            .map(CapsType::valueOf)
             .orElse(null);
     }
 
@@ -265,7 +292,9 @@ public class XDDFTextRun {
      *         Default is false.
      */
     public boolean isSubscript() {
-        return findDefinedProperty(props -> props.isSetBaseline(), props -> props.getBaseline())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetBaseline,
+                CTTextCharacterProperties::getBaseline)
             .map(baseline -> baseline < 0)
             .orElse(false);
     }
@@ -275,7 +304,9 @@ public class XDDFTextRun {
      *         Default is false.
      */
     public boolean isSuperscript() {
-        return findDefinedProperty(props -> props.isSetBaseline(), props -> props.getBaseline())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetBaseline,
+                CTTextCharacterProperties::getBaseline)
             .map(baseline -> baseline > 0)
             .orElse(false);
     }
@@ -332,8 +363,10 @@ public class XDDFTextRun {
     }
 
     public XDDFColor getFontColor() {
-        XDDFSolidFillProperties solid = findDefinedProperty(props -> props.isSetSolidFill(), props -> props.getSolidFill())
-            .map(props -> new XDDFSolidFillProperties(props))
+        XDDFSolidFillProperties solid = findDefinedProperty(
+                CTTextCharacterProperties::isSetSolidFill,
+                CTTextCharacterProperties::getSolidFill)
+            .map(XDDFSolidFillProperties::new)
             .orElse(new XDDFSolidFillProperties());
         return solid.getColor();
     }
@@ -352,18 +385,18 @@ public class XDDFTextRun {
     public XDDFFont[] getFonts() {
         LinkedList<XDDFFont> list = new LinkedList<>();
 
-        findDefinedProperty(props -> props.isSetCs(), props -> props.getCs())
+        findDefinedProperty(CTTextCharacterProperties::isSetCs, CTTextCharacterProperties::getCs)
             .map(font -> new XDDFFont(FontGroup.COMPLEX_SCRIPT, font))
-            .ifPresent(font -> list.add(font));
-        findDefinedProperty(props -> props.isSetEa(), props -> props.getEa())
+            .ifPresent(list::add);
+        findDefinedProperty(CTTextCharacterProperties::isSetEa, CTTextCharacterProperties::getEa)
             .map(font -> new XDDFFont(FontGroup.EAST_ASIAN, font))
-            .ifPresent(font -> list.add(font));
-        findDefinedProperty(props -> props.isSetLatin(), props -> props.getLatin())
+            .ifPresent(list::add);
+        findDefinedProperty(CTTextCharacterProperties::isSetLatin, CTTextCharacterProperties::getLatin)
             .map(font -> new XDDFFont(FontGroup.LATIN, font))
-            .ifPresent(font -> list.add(font));
-        findDefinedProperty(props -> props.isSetSym(), props -> props.getSym())
+            .ifPresent(list::add);
+        findDefinedProperty(CTTextCharacterProperties::isSetSym, CTTextCharacterProperties::getSym)
             .map(font -> new XDDFFont(FontGroup.SYMBOL, font))
-            .ifPresent(font -> list.add(font));
+            .ifPresent(list::add);
 
         return list.toArray(new XDDFFont[0]);
     }
@@ -384,7 +417,9 @@ public class XDDFTextRun {
     }
 
     public Double getFontSize() {
-        Integer size = findDefinedProperty(props -> props.isSetSz(), props -> props.getSz())
+        Integer size = findDefinedProperty(
+                CTTextCharacterProperties::isSetSz,
+                CTTextCharacterProperties::getSz)
             .orElse(100 * XSSFFont.DEFAULT_FONT_SIZE); // default font size
         double scale = _parent.getParentBody().getBodyProperties().getAutoFit().getFontScale() / 10_000_000.0;
         return size * scale;
@@ -415,7 +450,9 @@ public class XDDFTextRun {
      * If this attribute is omitted then returns <code>null</code>.
      */
     public Double getCharacterKerning() {
-        return findDefinedProperty(props -> props.isSetKern(), props -> props.getKern())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetKern,
+                CTTextCharacterProperties::getKern)
             .map(kerning -> 0.01 * kerning)
             .orElse(null);
     }
@@ -449,7 +486,9 @@ public class XDDFTextRun {
      * If this attribute is omitted then returns <code>null</code>.
      */
     public Double getCharacterSpacing() {
-        return findDefinedProperty(props -> props.isSetSpc(), props -> props.getSpc())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetSpc,
+                CTTextCharacterProperties::getSpc)
             .map(spacing -> 0.01 * spacing)
             .orElse(null);
     }
@@ -459,7 +498,9 @@ public class XDDFTextRun {
     }
 
     public String getBookmark() {
-        return findDefinedProperty(props -> props.isSetBmk(), props -> props.getBmk())
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetBmk,
+                CTTextCharacterProperties::getBmk)
             .orElse(null);
     }
 
@@ -484,8 +525,10 @@ public class XDDFTextRun {
     }
 
     public XDDFHyperlink getHyperlink() {
-        return findDefinedProperty(props -> props.isSetHlinkClick(), props -> props.getHlinkClick())
-            .map(link -> new XDDFHyperlink(link))
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetHlinkClick,
+                CTTextCharacterProperties::getHlinkClick)
+            .map(XDDFHyperlink::new)
             .orElse(null);
     }
 
@@ -496,8 +539,10 @@ public class XDDFTextRun {
     }
 
     public XDDFHyperlink getMouseOver() {
-        return findDefinedProperty(props -> props.isSetHlinkMouseOver(), props -> props.getHlinkMouseOver())
-            .map(link -> new XDDFHyperlink(link))
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetHlinkMouseOver,
+                CTTextCharacterProperties::getHlinkMouseOver)
+            .map(XDDFHyperlink::new)
             .orElse(null);
     }
 
@@ -506,8 +551,10 @@ public class XDDFTextRun {
     }
 
     public Locale getLanguage() {
-        return findDefinedProperty(props -> props.isSetLang(), props -> props.getLang())
-            .map(lang -> Locale.forLanguageTag(lang))
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetLang,
+                CTTextCharacterProperties::getLang)
+            .map(Locale::forLanguageTag)
             .orElse(null);
     }
 
@@ -516,8 +563,10 @@ public class XDDFTextRun {
     }
 
     public Locale getAlternativeLanguage() {
-        return findDefinedProperty(props -> props.isSetAltLang(), props -> props.getAltLang())
-            .map(lang -> Locale.forLanguageTag(lang))
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetAltLang,
+                CTTextCharacterProperties::getAltLang)
+            .map(Locale::forLanguageTag)
             .orElse(null);
     }
 
@@ -526,8 +575,10 @@ public class XDDFTextRun {
     }
 
     public XDDFColor getHighlight() {
-        return findDefinedProperty(props -> props.isSetHighlight(), props -> props.getHighlight())
-            .map(color -> XDDFColor.forColorContainer(color))
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetHighlight,
+                CTTextCharacterProperties::getHighlight)
+            .map(XDDFColor::forColorContainer)
             .orElse(null);
     }
 
@@ -536,14 +587,16 @@ public class XDDFTextRun {
     }
 
     public XDDFLineProperties getLineProperties() {
-        return findDefinedProperty(props -> props.isSetLn(), props -> props.getLn())
-            .map(props -> new XDDFLineProperties(props))
+        return findDefinedProperty(
+                CTTextCharacterProperties::isSetLn,
+                CTTextCharacterProperties::getLn)
+            .map(XDDFLineProperties::new)
             .orElse(null);
     }
 
-    private <R> Optional<R> findDefinedProperty(Function<CTTextCharacterProperties, Boolean> isSet, Function<CTTextCharacterProperties, R> getter) {
+    private <R> Optional<R> findDefinedProperty(Predicate<CTTextCharacterProperties> isSet, Function<CTTextCharacterProperties, R> getter) {
         CTTextCharacterProperties props = getProperties();
-        if (props != null && isSet.apply(props)) {
+        if (props != null && isSet.test(props)) {
             return Optional.ofNullable(getter.apply(props));
         } else {
             return _parent.findDefinedRunProperty(isSet, getter);
diff --git a/src/ooxml/java/org/apache/poi/xslf/usermodel/XSLFTextShape.java b/src/ooxml/java/org/apache/poi/xslf/usermodel/XSLFTextShape.java
index 0ba39d520f..b0dce8b7de 100644
--- a/src/ooxml/java/org/apache/poi/xslf/usermodel/XSLFTextShape.java
+++ b/src/ooxml/java/org/apache/poi/xslf/usermodel/XSLFTextShape.java
@@ -26,6 +26,7 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Optional;
 import java.util.function.Function;
+import java.util.function.Predicate;
 
 import org.apache.poi.ooxml.POIXMLException;
 import org.apache.poi.sl.draw.DrawFactory;
@@ -773,14 +774,14 @@ public abstract class XSLFTextShape extends XSLFSimpleShape
     }
 
     @Override
-    public <R> Optional<R> findDefinedParagraphProperty(Function<CTTextParagraphProperties, Boolean> isSet,
+    public <R> Optional<R> findDefinedParagraphProperty(Predicate<CTTextParagraphProperties> isSet,
         Function<CTTextParagraphProperties, R> getter) {
         // TODO Auto-generated method stub
         return Optional.empty();
     }
 
     @Override
-    public <R> Optional<R> findDefinedRunProperty(Function<CTTextCharacterProperties, Boolean> isSet,
+    public <R> Optional<R> findDefinedRunProperty(Predicate<CTTextCharacterProperties> isSet,
         Function<CTTextCharacterProperties, R> getter) {
         // TODO Auto-generated method stub
         return Optional.empty();
diff --git a/src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFSimpleShape.java b/src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFSimpleShape.java
index 92a173e743..dfc7a69466 100644
--- a/src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFSimpleShape.java
+++ b/src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFSimpleShape.java
@@ -23,6 +23,7 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Optional;
 import java.util.function.Function;
+import java.util.function.Predicate;
 
 import org.apache.poi.hssf.util.HSSFColor;
 import org.apache.poi.ss.usermodel.SimpleShape;
@@ -1005,14 +1006,14 @@ public class XSSFSimpleShape extends XSSFShape implements Iterable<XSSFTextParag
     }
 
     @Override
-    public <R> Optional<R> findDefinedParagraphProperty(Function<CTTextParagraphProperties, Boolean> isSet,
+    public <R> Optional<R> findDefinedParagraphProperty(Predicate<CTTextParagraphProperties> isSet,
         Function<CTTextParagraphProperties, R> getter) {
         // TODO Auto-generated method stub
         return Optional.empty();
     }
 
     @Override
-    public <R> Optional<R> findDefinedRunProperty(Function<CTTextCharacterProperties, Boolean> isSet,
+    public <R> Optional<R> findDefinedRunProperty(Predicate<CTTextCharacterProperties> isSet,
         Function<CTTextCharacterProperties, R> getter) {
         // TODO Auto-generated method stub
         return Optional.empty();