code: public <T extends IGeneratorParameter<?>> T getParameter(Class<T> param) {
          if (renderingParameters.containsKey(param.getName())) return (T) renderingParameters.get(param.getName());
  
          // the parameter was not registered yet, so we throw an exception to
          // indicate that the API is not used correctly.
          throw new IllegalAccessError("You requested the active parameter of type " + param.getName() + ", but it "
                  + "has not been registered yet. Did you " + "make sure the IGeneratorParameter is registered, by "
                  + "registring the appropriate IGenerator? Alternatively, "
                  + "you can use getDefault() to query the default value for " + "any parameter on the classpath.");
      }
docs: Returns the {@link IGeneratorParameter} for the active {@link IRenderer}.
  It returns a new instance of it was unregistered.
  
  @param param {@link IGeneratorParameter} to get the value of.
  @return the {@link IGeneratorParameter} instance with the active value.