diff --git a/poi-ooxml/src/main/java/org/apache/poi/openxml4j/opc/ZipPackage.java b/poi-ooxml/src/main/java/org/apache/poi/openxml4j/opc/ZipPackage.java
index af1a4c07b1..bf91ad17b0 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/openxml4j/opc/ZipPackage.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/openxml4j/opc/ZipPackage.java
@@ -537,8 +537,8 @@ public final class ZipPackage extends OPCPackage {
         try {
             // If the core properties part does not exist in the part list,
             // we save it as well
-            if (this.getPartsByRelationshipType(PackageRelationshipTypes.CORE_PROPERTIES).size() == 0 &&
-                this.getPartsByRelationshipType(PackageRelationshipTypes.CORE_PROPERTIES_ECMA376).size() == 0    ) {
+            if (this.getPartsByRelationshipType(PackageRelationshipTypes.CORE_PROPERTIES).isEmpty() &&
+                this.getPartsByRelationshipType(PackageRelationshipTypes.CORE_PROPERTIES_ECMA376).isEmpty()) {
                 LOG.atDebug().log("Save core properties part");
 
                 // Ensure that core properties are added if missing
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFBReader.java b/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFBReader.java
index d9a24bb855..9a02bcb4a0 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFBReader.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFBReader.java
@@ -108,7 +108,7 @@ public class XSSFBReader extends XSSFReader {
 
     public XSSFBStylesTable getXSSFBStylesTable() throws IOException {
         ArrayList<PackagePart> parts = pkg.getPartsByContentType(XSSFBRelation.STYLES_BINARY.getContentType());
-        if(parts.size() == 0) return null;
+        if(parts.isEmpty()) return null;
 
         // Create the Styles Table, and associate the Themes if present
         try (InputStream stream = parts.get(0).getInputStream()) {
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFReader.java b/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFReader.java
index 220f5b89c4..64ed7297ee 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFReader.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xssf/eventusermodel/XSSFReader.java
@@ -144,7 +144,7 @@ public class XSSFReader {
     public SharedStrings getSharedStringsTable() throws IOException, InvalidFormatException {
         ArrayList<PackagePart> parts = pkg.getPartsByContentType(XSSFRelation.SHARED_STRINGS.getContentType());
         try {
-            return parts.size() == 0 ? null :
+            return parts.isEmpty() ? null :
                     useReadOnlySharedStringsTable ? new ReadOnlySharedStringsTable(parts.get(0)) :
                             new SharedStringsTable(parts.get(0));
         } catch (SAXException se) {
@@ -158,7 +158,7 @@ public class XSSFReader {
      */
     public StylesTable getStylesTable() throws IOException, InvalidFormatException {
         ArrayList<PackagePart> parts = pkg.getPartsByContentType(XSSFRelation.STYLES.getContentType());
-        if (parts.size() == 0) return null;
+        if (parts.isEmpty()) return null;
 
         // Create the Styles Table, and associate the Themes if present
         StylesTable styles = new StylesTable(parts.get(0));
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xssf/streaming/SXSSFSheet.java b/poi-ooxml/src/main/java/org/apache/poi/xssf/streaming/SXSSFSheet.java
index d4e22810b2..38ff3d3e09 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xssf/streaming/SXSSFSheet.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xssf/streaming/SXSSFSheet.java
@@ -198,7 +198,7 @@ public class SXSSFSheet implements Sheet, OoxmlSheetExtensions {
         if(_writer.getNumberOfFlushedRows() > 0) {
             return _writer.getLowestIndexOfFlushedRows();
         }
-        return _rows.size() == 0 ? -1 : _rows.firstKey();
+        return _rows.isEmpty() ? -1 : _rows.firstKey();
     }
 
     /**
@@ -208,7 +208,7 @@ public class SXSSFSheet implements Sheet, OoxmlSheetExtensions {
      */
     @Override
     public int getLastRowNum() {
-        return _rows.size() == 0 ? -1 : _rows.lastKey();
+        return _rows.isEmpty() ? -1 : _rows.lastKey();
     }
 
     /**
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFRow.java b/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFRow.java
index 85543d5ff0..15859f4fdb 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFRow.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFRow.java
@@ -304,7 +304,7 @@ public class XSSFRow implements Row, Comparable<XSSFRow> {
      */
     @Override
     public short getFirstCellNum() {
-        return (short)(_cells.size() == 0 ? -1 : _cells.firstKey());
+        return (short)(_cells.isEmpty() ? -1 : _cells.firstKey());
     }
 
     /**
@@ -328,7 +328,7 @@ public class XSSFRow implements Row, Comparable<XSSFRow> {
      */
     @Override
     public short getLastCellNum() {
-        return (short)(_cells.size() == 0 ? -1 : (_cells.lastKey() + 1));
+        return (short)(_cells.isEmpty() ? -1 : (_cells.lastKey() + 1));
     }
 
     /**
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFSheet.java b/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFSheet.java
index 9f69900ec8..50ab442b15 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFSheet.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFSheet.java
@@ -2835,7 +2835,7 @@ public class XSSFSheet extends POIXMLDocumentPart implements Sheet, OoxmlSheetEx
      */
     @Beta
     public void copyRows(List<? extends Row> srcRows, int destStartRow, CellCopyPolicy policy) {
-        if (srcRows == null || srcRows.size() == 0) {
+        if (srcRows == null || srcRows.isEmpty()) {
             throw new IllegalArgumentException("No rows to copy");
         }
         final Row srcStartRow = srcRows.get(0);
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFWorkbook.java b/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFWorkbook.java
index ec17fa8809..0552d8182f 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFWorkbook.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xssf/usermodel/XSSFWorkbook.java
@@ -1383,7 +1383,7 @@ public class XSSFWorkbook extends POIXMLDocument implements Workbook, Date1904Su
         sheets.remove(index);
 
         // only set new sheet if there are still some left
-        if(sheets.size() == 0) {
+        if(sheets.isEmpty()) {
             return;
         }
 
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFAbstractFootnoteEndnote.java b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFAbstractFootnoteEndnote.java
index 7c97b908cd..0be1a2f74b 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFAbstractFootnoteEndnote.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFAbstractFootnoteEndnote.java
@@ -503,7 +503,7 @@ public abstract class XWPFAbstractFootnoteEndnote  implements Iterable<XWPFParag
      */
     public XWPFTable createTable() {
         XWPFTable table = new XWPFTable(ctFtnEdn.addNewTbl(), this);
-        if (bodyElements.size() == 0) {
+        if (bodyElements.isEmpty()) {
             XWPFParagraph p = createParagraph();
             ensureFootnoteRef(p);
         }
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFDocument.java b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFDocument.java
index f65667c55d..7274f9bbe7 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFDocument.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFDocument.java
@@ -618,7 +618,7 @@ public class XWPFDocument extends POIXMLDocument implements Document, IBody {
      */
     private int getBodyElementSpecificPos(int pos, List<? extends IBodyElement> list) {
         // If there's nothing to find, skip it
-        if (list.size() == 0) {
+        if (list.isEmpty()) {
             return -1;
         }
 
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFHeaderFooter.java b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFHeaderFooter.java
index fea3e33b48..a839c587cf 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFHeaderFooter.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFHeaderFooter.java
@@ -603,7 +603,7 @@ public abstract class XWPFHeaderFooter extends POIXMLDocumentPart implements IBo
     @Override
     protected void prepareForCommit() {
         // must contain at least an empty paragraph
-        if (bodyElements.size() == 0) {
+        if (bodyElements.isEmpty()) {
             createParagraph();
         }
 
@@ -611,7 +611,7 @@ public abstract class XWPFHeaderFooter extends POIXMLDocumentPart implements IBo
         for (XWPFTable tbl : tables) {
             for (XWPFTableRow row : tbl.tableRows) {
                 for (XWPFTableCell cell : row.getTableCells()) {
-                    if (cell.getBodyElements().size() == 0) {
+                    if (cell.getBodyElements().isEmpty()) {
                         cell.addParagraph();
                     }
                 }
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFTable.java b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFTable.java
index 971ea0ffd5..00247afc92 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFTable.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFTable.java
@@ -237,10 +237,10 @@ public class XWPFTable implements IBodyElement, ISDTContents {
     /**
      * Add a new cell at the end of each row in this table, creating a new column.
      * If rows have different numbers of columns, will still append a cell to each row.
-     * Currently does not match the width of existing columns.
+     * Currently, does not match the width of existing columns.
      */
     public void addNewCol() {
-        if (tableRows.size() == 0) {
+        if (tableRows.isEmpty()) {
             createRow();
         }
         for (XWPFTableRow tableRow : tableRows) {
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFTableCell.java b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFTableCell.java
index b81cde1eee..fe3140613a 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFTableCell.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFTableCell.java
@@ -441,7 +441,7 @@ public class XWPFTableCell implements IBody, ICell {
     }
 
     public void setText(String text) {
-        XWPFParagraph par = (paragraphs.size() == 0) ? addParagraph() : paragraphs.get(0);
+        XWPFParagraph par = paragraphs.isEmpty() ? addParagraph() : paragraphs.get(0);
         par.createRun().setText(text);
     }
 
diff --git a/poi-ooxml/src/test/java/org/apache/poi/xssf/TestXSSFXLookupFunction.java b/poi-ooxml/src/test/java/org/apache/poi/xssf/TestXSSFXLookupFunction.java
index dbe7c956fc..81fe37b623 100644
--- a/poi-ooxml/src/test/java/org/apache/poi/xssf/TestXSSFXLookupFunction.java
+++ b/poi-ooxml/src/test/java/org/apache/poi/xssf/TestXSSFXLookupFunction.java
@@ -31,7 +31,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 /**
  * Testcase for function XLOOKUP()
  */
-public class TestXSSFXLookupFunction {
+class TestXSSFXLookupFunction {
 
     //https://support.microsoft.com/en-us/office/xlookup-function-b7fd680e-6d10-43e6-84f9-88eae8bf5929
 
diff --git a/poi-scratchpad/src/main/java/org/apache/poi/hwpf/model/CHPBinTable.java b/poi-scratchpad/src/main/java/org/apache/poi/hwpf/model/CHPBinTable.java
index 1d0a570791..3f2bd01081 100644
--- a/poi-scratchpad/src/main/java/org/apache/poi/hwpf/model/CHPBinTable.java
+++ b/poi-scratchpad/src/main/java/org/apache/poi/hwpf/model/CHPBinTable.java
@@ -242,7 +242,7 @@ public class CHPBinTable
                 }
             }
 
-            if ( chpxs.size() == 0 )
+            if ( chpxs.isEmpty() )
             {
                 LOG.atWarn().log("Text piece [{}; {}) has no CHPX. Creating new one.", box(startInclusive),box(boundary));
                 // create it manually
diff --git a/poi-scratchpad/src/main/java/org/apache/poi/hwpf/model/PAPBinTable.java b/poi-scratchpad/src/main/java/org/apache/poi/hwpf/model/PAPBinTable.java
index 675b62e8be..917c7d8958 100644
--- a/poi-scratchpad/src/main/java/org/apache/poi/hwpf/model/PAPBinTable.java
+++ b/poi-scratchpad/src/main/java/org/apache/poi/hwpf/model/PAPBinTable.java
@@ -215,7 +215,7 @@ public class PAPBinTable
                 lastPapxIndex = oldPapxSortedByEndPos.size() - 1;
             }
 
-            if ( papxs.size() == 0 )
+            if ( papxs.isEmpty() )
             {
                 LOG.atWarn().log("Paragraph [{}; {}) has no PAPX. Creating new one.", box(startInclusive),box(endExclusive));
                 // create it manually
diff --git a/poi-scratchpad/src/main/java/org/apache/poi/hwpf/usermodel/Range.java b/poi-scratchpad/src/main/java/org/apache/poi/hwpf/usermodel/Range.java
index a3fd882d64..08d3840e56 100644
--- a/poi-scratchpad/src/main/java/org/apache/poi/hwpf/usermodel/Range.java
+++ b/poi-scratchpad/src/main/java/org/apache/poi/hwpf/usermodel/Range.java
@@ -889,7 +889,7 @@ public class Range {
     private static int binarySearchStart( List<? extends PropertyNode<?>> rpl,
             int start )
     {
-        if ( rpl.size() == 0 )
+        if ( rpl.isEmpty())
             return -1;
         if ( rpl.get( 0 ).getStart() >= start )
             return 0;
diff --git a/poi/src/main/java/org/apache/poi/extractor/ExtractorFactory.java b/poi/src/main/java/org/apache/poi/extractor/ExtractorFactory.java
index 03a8278077..759e75e068 100644
--- a/poi/src/main/java/org/apache/poi/extractor/ExtractorFactory.java
+++ b/poi/src/main/java/org/apache/poi/extractor/ExtractorFactory.java
@@ -347,7 +347,7 @@ public final class ExtractorFactory {
         }
 
         // Create the extractors
-        if(dirs.size() == 0 && nonPOIFS.size() == 0){
+        if(dirs.isEmpty() && nonPOIFS.isEmpty()){
             return new POITextExtractor[0];
         }
 
diff --git a/poi/src/main/java/org/apache/poi/hssf/record/AbstractEscherHolderRecord.java b/poi/src/main/java/org/apache/poi/hssf/record/AbstractEscherHolderRecord.java
index 5d022a2605..0f1377aa03 100644
--- a/poi/src/main/java/org/apache/poi/hssf/record/AbstractEscherHolderRecord.java
+++ b/poi/src/main/java/org/apache/poi/hssf/record/AbstractEscherHolderRecord.java
@@ -117,7 +117,7 @@ public abstract class AbstractEscherHolderRecord extends Record {
     @Override
     public int getRecordSize() {
         byte[] rawData = getRawData();
-        if (escherRecords.size() == 0 && rawData != null) {
+        if (escherRecords.isEmpty() && rawData != null) {
             // XXX: It should be possible to derive this without concatenating the array, too.
             return rawData.length;
         }
diff --git a/poi/src/main/java/org/apache/poi/hssf/record/DrawingGroupRecord.java b/poi/src/main/java/org/apache/poi/hssf/record/DrawingGroupRecord.java
index 91d805a381..ee301fce45 100644
--- a/poi/src/main/java/org/apache/poi/hssf/record/DrawingGroupRecord.java
+++ b/poi/src/main/java/org/apache/poi/hssf/record/DrawingGroupRecord.java
@@ -82,7 +82,7 @@ public final class DrawingGroupRecord extends AbstractEscherHolderRecord {
     public int serialize(int offset, byte[] data)
     {
         byte[] rawData = getRawData();
-        if (getEscherRecords().size() == 0 && rawData != null)
+        if (getEscherRecords().isEmpty() && rawData != null)
         {
             return writeData( offset, data, rawData );
         }
@@ -117,8 +117,7 @@ public final class DrawingGroupRecord extends AbstractEscherHolderRecord {
     private int getRawDataSize() {
         List<EscherRecord> escherRecords = getEscherRecords();
         byte[] rawData = getRawData();
-        if (escherRecords.size() == 0 && rawData != null)
-        {
+        if (escherRecords.isEmpty() && rawData != null) {
             return rawData.length;
         }
         int size = 0;
diff --git a/poi/src/main/java/org/apache/poi/hssf/record/common/UnicodeString.java b/poi/src/main/java/org/apache/poi/hssf/record/common/UnicodeString.java
index 37fd7e0ec5..9769f3cb1f 100644
--- a/poi/src/main/java/org/apache/poi/hssf/record/common/UnicodeString.java
+++ b/poi/src/main/java/org/apache/poi/hssf/record/common/UnicodeString.java
@@ -337,7 +337,7 @@ public class UnicodeString implements Comparable<UnicodeString>, Duplicatable, G
 
     public void removeFormatRun(FormatRun r) {
       field_4_format_runs.remove(r);
-      if (field_4_format_runs.size() == 0) {
+      if (field_4_format_runs.isEmpty()) {
         field_4_format_runs = null;
         field_2_optionflags = richText.clearByte(field_2_optionflags);
       }
diff --git a/poi/src/main/java/org/apache/poi/hssf/usermodel/HSSFSheet.java b/poi/src/main/java/org/apache/poi/hssf/usermodel/HSSFSheet.java
index f77cc16205..0bc614264e 100644
--- a/poi/src/main/java/org/apache/poi/hssf/usermodel/HSSFSheet.java
+++ b/poi/src/main/java/org/apache/poi/hssf/usermodel/HSSFSheet.java
@@ -316,7 +316,7 @@ public final class HSSFSheet implements Sheet {
             _sheet.removeRow(hrow.getRowRecord());
 
             // if there are no more rows, then reset first/last
-            if(_rows.size() == 0) {
+            if(_rows.isEmpty()) {
                 _firstrow = -1;
                 _lastrow = -1;
             }
diff --git a/poi/src/main/java/org/apache/poi/poifs/eventfilesystem/POIFSReaderRegistry.java b/poi/src/main/java/org/apache/poi/poifs/eventfilesystem/POIFSReaderRegistry.java
index 2091eec512..3b2af081be 100644
--- a/poi/src/main/java/org/apache/poi/poifs/eventfilesystem/POIFSReaderRegistry.java
+++ b/poi/src/main/java/org/apache/poi/poifs/eventfilesystem/POIFSReaderRegistry.java
@@ -150,13 +150,11 @@ class POIFSReaderRegistry
     }
 
     private void dropDocument(final POIFSReaderListener listener,
-                              final DocumentDescriptor descriptor)
-    {
+                              final DocumentDescriptor descriptor) {
         Set<POIFSReaderListener> listeners = chosenDocumentDescriptors.get(descriptor);
 
         listeners.remove(listener);
-        if (listeners.size() == 0)
-        {
+        if (listeners.isEmpty()) {
             chosenDocumentDescriptors.remove(descriptor);
         }
     }
diff --git a/poi/src/main/java/org/apache/poi/poifs/filesystem/POIFSFileSystem.java b/poi/src/main/java/org/apache/poi/poifs/filesystem/POIFSFileSystem.java
index eba62568b9..6194efab28 100644
--- a/poi/src/main/java/org/apache/poi/poifs/filesystem/POIFSFileSystem.java
+++ b/poi/src/main/java/org/apache/poi/poifs/filesystem/POIFSFileSystem.java
@@ -583,7 +583,7 @@ public class POIFSFileSystem extends BlockStore
                 offset++;
 
                 // Chain it
-                if (_xbat_blocks.size() == 0) {
+                if (_xbat_blocks.isEmpty()) {
                     _header.setXBATStart(offset);
                 } else {
                     _xbat_blocks.get(_xbat_blocks.size() - 1).setValueAt(
diff --git a/poi/src/main/java/org/apache/poi/ss/format/CellFormatPart.java b/poi/src/main/java/org/apache/poi/ss/format/CellFormatPart.java
index c350f5f363..9ecc5ce53d 100644
--- a/poi/src/main/java/org/apache/poi/ss/format/CellFormatPart.java
+++ b/poi/src/main/java/org/apache/poi/ss/format/CellFormatPart.java
@@ -48,7 +48,7 @@ import static org.apache.poi.ss.format.CellFormatter.quote;
  */
 @SuppressWarnings("RegExpRepeatedSpace")
 public class CellFormatPart {
-    private static final Logger LOG = LogManager.getLogger(CellFormat.class.getName());
+    private static final Logger LOG = LogManager.getLogger(CellFormatPart.class);
 
     static final Map<String, Color> NAMED_COLORS;
 
diff --git a/poi/src/main/java/org/apache/poi/ss/formula/EvaluationConditionalFormatRule.java b/poi/src/main/java/org/apache/poi/ss/formula/EvaluationConditionalFormatRule.java
index b1c3504f2b..b3fb95f593 100644
--- a/poi/src/main/java/org/apache/poi/ss/formula/EvaluationConditionalFormatRule.java
+++ b/poi/src/main/java/org/apache/poi/ss/formula/EvaluationConditionalFormatRule.java
@@ -598,7 +598,7 @@ public class EvaluationConditionalFormatRule implements Comparable<EvaluationCon
         }
 
         final Set<ValueAndFormat> avgSet = new LinkedHashSet<>(1);
-        avgSet.add(new ValueAndFormat(allValues.size() == 0 ? 0 : total / allValues.size(), null, decimalTextFormat));
+        avgSet.add(new ValueAndFormat(allValues.isEmpty() ? 0 : total / allValues.size(), null, decimalTextFormat));
 
         final double stdDev = allValues.size() <= 1 ? 0 : ((NumberEval) AggregateFunction.STDEV.evaluate(pop, 0, 0)).getNumberValue();
         avgSet.add(new ValueAndFormat(stdDev, null, decimalTextFormat));
diff --git a/poi/src/main/java/org/apache/poi/ss/formula/atp/TextJoinFunction.java b/poi/src/main/java/org/apache/poi/ss/formula/atp/TextJoinFunction.java
index 14a17854f3..52fcb05cc0 100644
--- a/poi/src/main/java/org/apache/poi/ss/formula/atp/TextJoinFunction.java
+++ b/poi/src/main/java/org/apache/poi/ss/formula/atp/TextJoinFunction.java
@@ -93,7 +93,7 @@ final class TextJoinFunction implements FreeRefFunction {
             }
 
             // Join the list of values with the specified delimiter and return
-            if (delimiterArgs.size() == 0) {
+            if (delimiterArgs.isEmpty()) {
                 return new StringEval(String.join("", textValues));
             } else if (delimiterArgs.size() == 1) {
                 String delimiter = laxValueToString(delimiterArgs.get(0));
diff --git a/poi/src/main/java/org/apache/poi/ss/formula/functions/LookupUtils.java b/poi/src/main/java/org/apache/poi/ss/formula/functions/LookupUtils.java
index 648250beca..c76bfc0f4e 100644
--- a/poi/src/main/java/org/apache/poi/ss/formula/functions/LookupUtils.java
+++ b/poi/src/main/java/org/apache/poi/ss/formula/functions/LookupUtils.java
@@ -22,8 +22,6 @@ import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.NoSuchElementException;
-import java.util.Spliterator;
-import java.util.Spliterators;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;