code: public static Geometry ringSideBuffer(Geometry geom, double bufferSize, int numBuffer) throws SQLException {
          return ringSideBuffer(geom, bufferSize, numBuffer, "endcap=flat");
      }
docs: Compute a ring buffer on one side of the geometry
  @param geom
  @param bufferSize
  @param numBuffer
  @return
  @throws java.sql.SQLException