code: public Map<String, ExpressionMapping> getInputOutputExpressionMappings() {
          Map<String, ExpressionMapping> map = new LinkedHashMap<String, ExpressionMapping>();
          for (ExpressionMapping em : _inputExpressionMappings) {
              String output = em.getOutput();
              if (output != null) {
                  if (map.containsKey(output)) {
                      throw new IllegalArgumentException("duplicate input/output variable [" + output + "] not allowed");
                  } else {
                      map.put(output, em);
                  }
              }
          }
          return map;
      }
docs: Gets the input-output expression mappings.
  
  @return the input-output expression mappings