public static long readVLOld(DataInput in) throws IOException {
    byte code = in.readByte();
    long result;
    if (code < 0) {
      // mask off sign bit
      result = code & 0x7F;
      result <<= 8;
      result |= in.readByte() & 0xFF;
    } else if (code <= StaticSerialization.MAX_BYTE_VL) {
      result = code;
    } else if (code == StaticSerialization.INT_VL) {
      result = in.readInt();
    } else {
      result = in.readLong();
    }
    return result;
  }
Write a variable length long the old way (pre 7.0). Use this only in contexts where you might
need to communicate with pre 7.0 members or files.
geode-core/src/main/java/org/apache/geode/internal/InternalDataSerializer.java