code: public List validateSLD(InputSource xml) {
          URL schemaURL = SLDValidator.class.getResource("/schemas/sld/StyledLayerDescriptor.xsd");
          return ResponseUtils.validate(xml, schemaURL, false, entityResolver);
      }
docs: validate a .sld against the schema
  
  @param xml input stream representing the .sld file
  @return list of SAXExceptions (0 if the file's okay)