public String getParameterName() {
        if( parameterName == null ) {
            throw new NullPointerException( "Argument has no parameter name" );
        }
        return parameterName;
    }
@throws NullPointerException in case their is no parameter name
@return the parameter name if there is one
jgiven-core/src/main/java/com/tngtech/jgiven/report/model/ArgumentInfo.java