public static int writeByteArray(final byte[] tgt, final int tgtOffset, final byte[] src,
    final int srcOffset, final int srcLength) {
    byte[] vint = vintToBytes(srcLength);
    System.arraycopy(vint, 0, tgt, tgtOffset, vint.length);
    int offset = tgtOffset + vint.length;
    System.arraycopy(src, srcOffset, tgt, offset, srcLength);
    return offset + srcLength;
  }
Write byte-array from src to tgt with a vint length prefix.
@param tgt       target array
@param tgtOffset offset into target array
@param src       source array
@param srcOffset source offset
@param srcLength source length
@return New offset in src array.
hbase-common/src/main/java/org/apache/hadoop/hbase/util/Bytes.java