docs: public DefaultExpander getDslExpander() {
          DefaultExpander expander = new DefaultExpander();
          if (this.dslFiles == null || this.dslFiles.isEmpty()) {
              return null;
          }
          for (DSLMappingFile file : this.dslFiles) {
              expander.addDSLMapping(file.getMapping());
          }
          return expander;
      }