code: public void append(final int b) {
          final int newlen = this.len + 1;
          if (newlen > this.array.length) {
              expand(newlen);
          }
          this.array[this.len] = (byte)b;
          this.len = newlen;
      }
docs: Appends {@code b} byte to this buffer. The capacity of the buffer
  is increased, if necessary, to accommodate the additional byte.
  
  @param   b        the byte to be appended.