code: @Override
      public StringBuilder getFilterClause() {
          StringBuilder builder = new StringBuilder();
          builder.append(columnName);
          if (name.lastIndexOf('_') > 0) {
              String suffix = name.substring(name.lastIndexOf('_') + 1);
              if ("before".equals(suffix)) {
                  builder.append(" < ");
              } else if ("after".equals(suffix)) {
                  builder.append(" > ");
              } else {
                  builder.append(" = ");
              }
          } else {
              builder.append(" = ");
          }
          builder.append(':').append(name);
          return builder;
      }
docs: /* (non-Javadoc)
  @see org.talend.esb.sam.server.persistence.criterias.Criteria#getFilterClause()