Fixed failures and added javadocs

Author: siddharthteotia

java/vector/src/main/codegen/templates/NullableValueVectors.java

@@ -219,7 +219,7 @@ public int getBufferSizeFor(final int valueCount) {
   }
 
   public ArrowBuf getBuffer() {
-    return values.getBuffer();
+    return values.getDataBuffer();
   }
 
   @Override

java/vector/src/main/java/org/apache/arrow/vector/ValueVector.java

@@ -235,7 +235,24 @@ interface Mutator {
     void generateTestData(int values);
   }
 
-  public ArrowBuf getDataBuffer();
+  /**
+   * Gets the underlying buffer associated with validity vector
+   *
+   * @return buffer
+   */
   public ArrowBuf getValidityBuffer();
+
+  /**
+   * Gets the underlying buffer associated with data vector
+   *
+   * @return buffer
+   */
+  public ArrowBuf getDataBuffer();
+
+  /**
+   * Gets the underlying buffer associated with offset vector
+   *
+   * @return buffer
+   */
   public ArrowBuf getOffsetBuffer();
 }

java/vector/src/main/java/org/apache/arrow/vector/complex/FixedSizeListVector.java

@@ -309,17 +309,17 @@ public long getOffsetBufferAddress() {
   }
 
   @Override
-  public long getValidityBufferAddress() {
-    return (bits.getDataBuffer().memoryAddress());
+  public ArrowBuf getValidityBuffer() {
+    return (bits.getDataBuffer());
   }
 
   @Override
-  public long getDataBufferAddress() {
+  public ArrowBuf getDataBuffer() {
     throw new UnsupportedOperationException();
   }
 
   @Override
-  public long getOffsetBufferAddress() {
+  public ArrowBuf getOffsetBuffer() {
     throw new UnsupportedOperationException();
   }