[OLINGO-659] Minor code clean up

lib/server-core/src/main/java/org/apache/olingo/server/core/deserializer/batch/BatchBodyPart.java

@@ -87,7 +87,7 @@ public class BatchBodyPart implements BatchPart {
   private List<List<Line>> splitChangeSet(List<Line> remainingMessage) throws BatchDeserializerException {
 
     final HeaderField contentTypeField = headers.getHeaderField(HttpHeader.CONTENT_TYPE);
-    final String changeSetBoundary = BatchParserCommon.getBoundary(contentTypeField.getValueNotNull(),
+    final String changeSetBoundary = BatchParserCommon.getBoundary(contentTypeField.getValue(),
         contentTypeField.getLineNumber());
     validateChangeSetBoundary(changeSetBoundary, headers);
 

lib/server-core/src/main/java/org/apache/olingo/server/core/deserializer/batch/BatchParserCommon.java

@@ -46,9 +46,9 @@ public class BatchParserCommon {
   public static String getBoundary(final String contentType, final int line) throws BatchDeserializerException {
     final ContentType type = getContentType(contentType, ContentType.MULTIPART_MIXED, line);
     final Map<String, String> parameters = type.getParameters();
-    for (final String parameterName : parameters.keySet()) {
+    for (final Map.Entry<String, String> entries : parameters.entrySet()) {
-      if (BOUNDARY.equalsIgnoreCase(parameterName)) {
+      if (BOUNDARY.equalsIgnoreCase(entries.getKey())) {
-        final String boundary = parameters.get(parameterName).trim();
+        final String boundary = entries.getValue().trim();
         if (boundary.matches(PATTERN_BOUNDARY)) {
           return trimQuotes(boundary);
         } else {
@@ -63,7 +63,7 @@ public class BatchParserCommon {
 
   public static ContentType getContentType(final String contentType, final ContentType expected, final int line)
       throws BatchDeserializerException {
-    ContentType type = null;
+    ContentType type;
     try {
       type = ContentType.create(contentType);
     } catch (final IllegalArgumentException e) {
@@ -83,11 +83,6 @@ public class BatchParserCommon {
     }
   }
 
-  public static String removeEndingSlash(final String content) {
-    String newContent = content.trim();
-    return newContent.endsWith("/") ? newContent.substring(0, newContent.length() - 1) : newContent;
-  }
-
   private static String trimQuotes(final String boundary) {
     if (boundary != null && boundary.length() >= 2 && boundary.startsWith("\"") && boundary.endsWith("\"")) {
       return boundary.substring(1, boundary.length() - 1);

lib/server-core/src/main/java/org/apache/olingo/server/core/deserializer/batch/Header.java

@@ -73,12 +73,6 @@ public class Header implements Iterable<HeaderField> {
     return (headerField == null) ? null : headerField.getValue();
   }
 
-  public String getHeaderNotNull(final String name) {
-    final HeaderField headerField = getHeaderField(name);
-
-    return (headerField == null) ? "" : headerField.getValueNotNull();
-  }
-
   public List<String> getHeaders(final String name) {
     final HeaderField headerField = getHeaderField(name);
 
@@ -96,9 +90,9 @@ public class Header implements Iterable<HeaderField> {
   public Map<String, String> toSingleMap() {
     final Map<String, String> singleMap = new HashMap<String, String>();
 
-    for (final String key : headers.keySet()) {
+    for (final Map.Entry<String, HeaderField> entries : headers.entrySet()) {
-      HeaderField field = headers.get(key);
+      HeaderField field = entries.getValue();
-      singleMap.put(field.getFieldName(), getHeader(key));
+      singleMap.put(field.getFieldName(), getHeader(entries.getKey()));
     }
 
     return singleMap;
@@ -107,8 +101,8 @@ public class Header implements Iterable<HeaderField> {
   public Map<String, List<String>> toMultiMap() {
     final Map<String, List<String>> singleMap = new HashMap<String, List<String>>();
 
-    for (final String key : headers.keySet()) {
+    for (final Map.Entry<String, HeaderField> entries : headers.entrySet()) {
-      HeaderField field = headers.get(key);
+      HeaderField field = entries.getValue();
       singleMap.put(field.getFieldName(), field.getValues());
     }
 
@@ -130,8 +124,8 @@ public class Header implements Iterable<HeaderField> {
   public Header clone() {
     final Header newInstance = new Header(lineNumber);
 
-    for (final String key : headers.keySet()) {
+    for (final Map.Entry<String, HeaderField> entries : headers.entrySet()) {
-      newInstance.headers.put(key, headers.get(key).clone());
+      newInstance.headers.put(entries.getKey(), entries.getValue().clone());
     }
 
     return newInstance;

lib/server-core/src/main/java/org/apache/olingo/server/core/deserializer/batch/HeaderField.java

@@ -59,15 +59,9 @@ public class HeaderField implements Cloneable {
     return result.toString();
   }
 
-  public String getValueNotNull() {
-    final String value = getValue();
-
-    return (value == null) ? "" : value;
-  }
-
   @Override
   public HeaderField clone() {
-    List<String> newValues = new ArrayList<String>();
+    List<String> newValues = new ArrayList<String>(values.size());
     newValues.addAll(values);
 
     return new HeaderField(fieldName, newValues, lineNumber);

lib/server-core/src/main/java/org/apache/olingo/server/core/prefer/PreferParser.java

@@ -102,9 +102,9 @@ public class PreferParser {
     }
     if (matcher.hitEnd()) {
       // Here we also have to keep already existing preferences.
-      for (final String key : partResult.keySet()) {
+      for (final Map.Entry<String, Preference> entry : partResult.entrySet()) {
-        if (!result.containsKey(key)) {
+        if (!result.containsKey(entry.getKey())) {
-          result.put(key, partResult.get(key));
+          result.put(entry.getKey(), entry.getValue());
         }
       }
     }

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/AsyncResponseSerializer.java

@@ -61,8 +61,8 @@ public class AsyncResponseSerializer {
                                     final ByteArrayOutputStream buffer) throws IOException {
     final Map<String, String> header = response.getHeaders();
 
-    for (final String key: header.keySet()) {
+    for (final Map.Entry<String, String> entry: header.entrySet()) {
-      appendHeader(key, header.get(key), buffer);
+      appendHeader(entry.getKey(), entry.getValue(), buffer);
     }
   }
 

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/BatchResponseSerializer.java

@@ -105,7 +105,7 @@ public class BatchResponseSerializer {
 
   private void appendChangeSetHeader(final BodyBuilder builder, final String changeSetBoundary) {
     appendHeader(HttpHeader.CONTENT_TYPE, HttpContentType.MULTIPART_MIXED + "; boundary="
-        + changeSetBoundary, builder);
+            + changeSetBoundary, builder);
   }
 
   private void appendHeader(final String name, final String value, final BodyBuilder builder) {
@@ -121,18 +121,26 @@ public class BatchResponseSerializer {
         .append(SP)
         .append(response.getStatusCode())
         .append(SP)
-        .append(HttpStatusCode.fromStatusCode(response.getStatusCode()).toString())
+        .append(getStatusCodeInfo(response))
         .append(CRLF);
   }
 
+  private String getStatusCodeInfo(ODataResponse response) {
+    HttpStatusCode status = HttpStatusCode.fromStatusCode(response.getStatusCode());
+    if(status == null) {
+      throw new ODataRuntimeException("Invalid status code in response '" + response.getStatusCode() + "'");
+    }
+    return status.getInfo();
+  }
+
   private void appendResponseHeader(final ODataResponse response, final int contentLength,
       final BodyBuilder builder) {
     final Map<String, String> header = response.getHeaders();
 
-    for (final String key : header.keySet()) {
+    for (final Map.Entry<String, String> entry : header.entrySet()) {
       // Requests do never has a content id header
-      if (!key.equalsIgnoreCase(HttpHeader.CONTENT_ID)) {
+      if (!entry.getKey().equalsIgnoreCase(HttpHeader.CONTENT_ID)) {
-        appendHeader(key, header.get(key), builder);
+        appendHeader(entry.getKey(), entry.getValue(), builder);
       }
     }
 

lib/server-core/src/test/java/org/apache/olingo/server/core/deserializer/batch/HeaderTest.java

@@ -47,7 +47,6 @@ public class HeaderTest {
 
     assertNull(header.getHeader(HttpHeader.CONTENT_TYPE));
     assertEquals(0, header.getHeaders(HttpHeader.CONTENT_TYPE).size());
-    assertEquals("", header.getHeaderNotNull(HttpHeader.CONTENT_TYPE));
   }
 
   @Test