#vulnerable code 
                                public void execute() {
        getLog().info("Starting " + this.getClass().getSimpleName() + "...");
        RevengStrategy strategy = setupReverseEngineeringStrategy();
        Properties properties = loadPropertiesFile();
        MetadataDescriptor jdbcDescriptor = createJdbcDescriptor(strategy, properties);
        executeExporter(jdbcDescriptor);
        getLog().info("Finished " + this.getClass().getSimpleName() + "!");
    } 
                            #location 5 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public void execute() {
        getLog().info("Starting " + this.getClass().getSimpleName() + "...");
        RevengStrategy strategy = setupReverseEngineeringStrategy();
        if (propertyFile.exists()) {
        	executeExporter(createJdbcDescriptor(strategy, loadPropertiesFile()));
        } else {
        	getLog().info("Property file '" + propertyFile + "' cannot be found, aborting...");
        }
        getLog().info("Finished " + this.getClass().getSimpleName() + "!");
    }