[Java]: Expose util methods inside VectorAppender class such as append vector values

[davisusanibar]

Describe the enhancement requested

Current VectorAppender class is package-private.

This class provides utility methods for appending vector values fields that can be exposed publicly.

Java code:

 package org.apache.arrow.vector.util;
 import org.apache.arrow.memory.BufferAllocator;
 import org.apache.arrow.memory.RootAllocator;
 import org.apache.arrow.vector.IntVector;
 import org.apache.arrow.vector.ValueVector;
 public class FieldVectorAppender {
 public static void main(String[] args) {
 try (
 BufferAllocator allocator = new RootAllocator();
 IntVector initialValues = new IntVector("initialValues", allocator);
 IntVector toAppend = new IntVector("toAppend", allocator);
 ) {
 initialValues.allocateNew(2);
 initialValues.set(0, 1);
 initialValues.set(1, 2);
 initialValues.setValueCount(2);
 System.out.println("Initial IntVector: " + initialValues);
 toAppend.allocateNew(4);
 toAppend.set(1, 4);
 toAppend.set(3, 6);
 toAppend.setValueCount(4);
 System.out.println("IntVector to Append: " + toAppend);
 VectorAppender appenderUtil = new VectorAppender(initialValues);
 ValueVector resultOfVectorsAppended = toAppend.accept(appenderUtil, null);
 System.out.println("IntVector Result: " + resultOfVectorsAppended);
 }
 }
 }

Result:

 Initial IntVector: [1, 2]
 IntVector to Append: [null, 4, null, 6]
 IntVector Result: [1, 2, null, 4, null, 6]

Component(s)

Java