code: public InputVariable getInputVariable(String name) {
          for (InputVariable inputVariable : this.inputVariables) {
              if (name.equals(inputVariable.getName())) {
                  return inputVariable;
              }
          }
          throw new RuntimeException(String.format(
                  "[engine error] no input variable by name <%s>", name));
      }
docs: Gets the input variable of the given name after iterating the input
  variables. The cost of this method is O(n), where n is the number of input
  variables in the engine. For performance, please get the variables by
  index.
  
  @param name is the name of the input variable
  @return input variable of the given name
  @throws RuntimeException if there is no variable with the given name