code: public String getModuleParamString(String moduleName, String paramName) {
          Map<String, Object> moduleParams = getModuleParams(moduleName);
          if (moduleParams == null || !moduleParams.containsKey(paramName)) {
              return null;
          }
          return moduleParams.get(paramName).toString();
      }
docs: Get the String value of the given parameter name belonging to the given module
  name. If no such module/parameter name is known, null is returned. If the parameter
  exists, a string is created by calling toString().
  
  @param moduleName    Name of module to get parameter for.
  @param paramName     Name of parameter to get value of.
  @return              Parameter value as a String or null if known.