Incorrect instruction element length handle because of Java's char type

The definition of guacamole instruction:

The Guacamole protocol consists of instructions. Each instruction is a comma-delimited list followed by a terminating semicolon, where the first element of the list is the instruction opcode, and all following elements are the arguments for that instruction:

OPCODE,ARG1,ARG2,ARG3,...;

Each element of the list has a positive decimal integer length prefix separated by the value of the element by a period. This length denotes the number of Unicode characters in the value of the element, which is encoded in UTF-8:

 

LENGTH.VALUE

Which means the element's values will be encoded in UTF-8。That means we must use correct UTF-8 encoder/decoder to handle the instruction. But in guacamole-common, the parser use Java's char type to parse which only can store partial Unicode char. 

Problem code https://github.com/apache/guacamole-client/blob/master/guacamole-common/src/main/java/org/apache/guacamole/protocol/GuacamoleParser.java#L164  

if (state == State.PARSING_CONTENT && charsParsed + elementLength + 1 <= length) {

// Read element
String element = new String(chunk, offset + charsParsed, elementLength);
charsParsed += elementLength;
elementLength = 0;
...

In the code above, bytes of a unicode char may not equal to a java char.

I also check the guacamole-server implementation, all work fine.

Correct code https://github.com/apache/guacamole-server/blob/master/src/libguac/parser.c#L113

/* Advance to next character */
parser->__element_length--;
char_buffer += char_length;