code: public void checkConfiguration(final AbstractInvokable invokable) throws IllegalConfigurationException {
  
  		if (invokable == null) {
  			throw new IllegalArgumentException("Argument invokable is null");
  		}
  
  		// see if the task itself has a valid configuration
  		// because this is user code running on the master, we embed it in a catch-all block
  		try {
  			invokable.checkConfiguration();
  		} catch (IllegalConfigurationException icex) {
  			throw icex; // simply forward
  		} catch (Throwable t) {
  			throw new IllegalConfigurationException("Checking the invokable's configuration caused an error: "
  				+ StringUtils.stringifyException(t));
  		}
  	}
docs: Performs task specific checks if the
  respective task has been configured properly.
  
  @param invokable
  an instance of the task this vertex represents
  @throws IllegalConfigurationException
  thrown if the respective tasks is not configured properly