@Override
  public void addElements(final int index, final K[] a, final int offset, final int length) {
    ensureIndex(index);
    ObjectArrays.ensureOffsetLength(a, offset, length);
    grow(size + length);
    System.arraycopy(this.a, index, this.a, index + length, size - index);
    System.arraycopy(a, offset, this.a, index, length);
    size += length;
  }
Adds elements to this type-specific list using optimized system calls.

@param index the index at which to add elements.
@param a the array containing the elements.
@param offset the offset of the first element to add.
@param length the number of elements to add.
geode-core/src/main/java/org/apache/geode/internal/cache/IdentityArrayList.java