[OLINGO-1499]Fix case-sensitive handling of Content-Type header in BatchLineReader

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

@@ -24,6 +24,7 @@ import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 import org.apache.olingo.commons.api.format.ContentType;
 import org.apache.olingo.commons.api.http.HttpHeader;
@@ -95,7 +96,7 @@ public class BatchLineReader {
 
   private void updateCurrentCharset(final String currentLine) {
     if (currentLine != null) {
-      if (currentLine.startsWith(HttpHeader.CONTENT_TYPE)) {
+      if (currentLine.toLowerCase(Locale.ENGLISH).startsWith(HttpHeader.CONTENT_TYPE.toLowerCase(Locale.ENGLISH))) {
         int cutOff = currentLine.endsWith(CRLF) ? 2 : currentLine.endsWith(LFS) ? 1 : 0;
         final ContentType contentType = ContentType.parse(
             currentLine.substring(HttpHeader.CONTENT_TYPE.length() + 1, currentLine.length() - cutOff).trim());

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

@@ -270,6 +270,21 @@ public class BatchLineReaderTest {
     reader.close();
   }
 
+  @Test
+  public void specialCharactersInJsonWithLowercaseContentType() throws Exception {
+    final String text = "\n"
+        + "content-type: application/json\n"
+        + "\n"
+        + "{\"text\": \"ä€ß\"}\n";
+    BatchLineReader reader = create(text);
+    reader.readLine();
+    reader.readLine();
+    reader.readLine();
+    assertEquals("{\"text\": \"ä€ß\"}\n", reader.readLine());
+    assertNull(reader.readLine());
+    reader.close();
+  }
+
   @Test
   public void rawBytes() throws Exception {
     byte[] content = new byte[Byte.MAX_VALUE - Byte.MIN_VALUE + 1];