docs: public Message setBuffer(byte[] b, int offset, int length) {
          buf=b;
          if(buf != null) {
              if(offset < 0 || offset > buf.length)
                  throw new ArrayIndexOutOfBoundsException(offset);
              if((offset + length) > buf.length)
                  throw new ArrayIndexOutOfBoundsException((offset+length));
              this.offset=offset;
              this.length=length;
          }
          else
              this.offset=this.length=0;
          return this;
      }