anchor.diff:  ///  * null: null
   ///  * [bool]\: `java.lang.Boolean`
   ///  * [int]\: `java.lang.Integer` for values that are representable using 32-bit
  -///    two's complement; otherwise, `java.lang.Long` for values that are
  -///    representable using 64-bit two's complement; otherwise,
  -///    `java.math.BigInteger`.
  +///    two's complement; `java.lang.Long` otherwise
   ///  * [double]\: `java.lang.Double`
   ///  * [String]\: `java.lang.String`
   ///  * [Uint8List]\: `byte[]`
  
positive.code: ///  * null: nil
  ///  * [bool]\: `NSNumber numberWithBool:`
  ///  * [int]\: `NSNumber numberWithInt:` for values that are representable using
  ///    32-bit two's complement; otherwise, `NSNumber numberWithLong:` for values
  ///    that are representable using 64-bit two's complement; otherwise,
  ///    `FlutterStandardBigInteger`.
  ///  * [double]\: `NSNumber numberWithDouble:`
  ///  * [String]\: `NSString`
  ///  * [Uint8List], [Int32List], [Int64List], [Float64List]\:
  
negative.code:       if (-0x7fffffff - 1 <= value && value <= 0x7fffffff) {
          buffer.putUint8(_kInt32);
          buffer.putInt32(value);
        } else {
          buffer.putUint8(_kInt64);
          buffer.putInt64(value);
        }
      } else if (value is double) {
        buffer.putUint8(_kFloat64);
  