code: public static Charset getTemplateOutputEncoding(Configuration configuration, String suffix) {
          final String enc = PropertiesHelper.getValue(configuration.getProperties(), MvcFeature.ENCODING + suffix,
                  String.class, null);
          if (enc == null) {
              return DEFAULT_ENCODING;
          } else {
              return Charset.forName(enc);
          }
      }
docs: Get output encoding from configuration.
  
  @param configuration Configuration.
  @param suffix        Template processor suffix of the
  to configuration property {@link org.glassfish.jersey.server.mvc.MvcFeature#ENCODING}.
  @return Encoding read from configuration properties or a default encoding if no encoding is configured.