code: public static DynamicByteBuffer createExact( final int capacity ) {
          return new DynamicByteBuffer( capacity ) {
              public DynamicByteBuffer add( byte[] chars ) {
                  DynamicByteBufferHelper._idx( buffer, length, chars );
                  length += chars.length;
                  return this;
              }
          };
      }
docs: Creates the exact.
  
  @param capacity the capacity
  @return the dynamic byte buffer