#vulnerable code 
                                private void reportErrorIfPropertyCanNotBeMapped(Method method, PropertyMapping property) {
        if ( property.getSourceType().equals( property.getTargetType() ) ||
            property.getMappingMethod() != null ||
            property.getConversion() != null ||
            property.getTargetType().getImplementationType() != null ) {
            return;
        }

        messager.printMessage(
            Kind.ERROR,
            String.format(
                "Can't map property \"%s %s\" to \"%s %s\".",
                property.getSourceType().getName(),
                property.getSourceName(),
                property.getTargetType().getName(),
                property.getTargetName()
            ),
            method.getExecutable()
        );
    } 
                            #location 5 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                private void reportErrorIfPropertyCanNotBeMapped(Method method, PropertyMapping property) {
        if ( property.getSourceType().isAssignableTo( property.getTargetType() ) ||
            property.getMappingMethod() != null ||
            property.getConversion() != null ||
            property.getTargetType().getImplementationType() != null ) {
            return;
        }

        messager.printMessage(
            Kind.ERROR,
            String.format(
                "Can't map property \"%s %s\" to \"%s %s\".",
                property.getSourceType(),
                property.getSourceName(),
                property.getTargetType(),
                property.getTargetName()
            ),
            method.getExecutable()
        );
    }