#vulnerable code 
                                private PropertyMapping getPropertyMapping(List<MapperReference> mapperReferences, List<Method> methods,
                                               Method method, Parameter parameter, ExecutableElement sourceAccessor,
                                               ExecutableElement targetAcessor, String dateFormat) {
        Type sourceType = typeFactory.getReturnType( sourceAccessor );
        Type targetType = null;
        String conversionString = null;
        conversionString = parameter.getName() + "." + sourceAccessor.getSimpleName().toString() + "()";

        if ( Executables.isSetterMethod( targetAcessor ) ) {
            targetType = typeFactory.getSingleParameter( targetAcessor ).getType();
        }
        else if ( Executables.isGetterMethod( targetAcessor ) ) {
            targetType = typeFactory.getReturnType( targetAcessor );
        }

        MethodReference propertyMappingMethod = getMappingMethodReference(
            mapperReferences,
            methods,
            sourceType,
            targetType
        );
        TypeConversion conversion = getConversion(
            sourceType,
            targetType,
            dateFormat,
            conversionString
        );

        PropertyMapping property = new PropertyMapping(
            parameter.getName(),
            Executables.getPropertyName( sourceAccessor ),
            sourceAccessor.getSimpleName().toString(),
            sourceType,
            Executables.getPropertyName( targetAcessor ),
            targetAcessor.getSimpleName().toString(),
            targetType,
            propertyMappingMethod,
            conversion
        );

        reportErrorIfPropertyCanNotBeMapped(
            method,
            property
        );

        return property;
    } 
                            #location 10 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                private PropertyMapping getPropertyMapping(List<MapperReference> mapperReferences, List<Method> methods,
                                               Method method, Parameter parameter, ExecutableElement sourceAccessor,
                                               ExecutableElement targetAcessor, String dateFormat) {
        Type sourceType = typeFactory.getReturnType( sourceAccessor );
        Type targetType = null;
        String conversionString = null;
        conversionString = parameter.getName() + "." + sourceAccessor.getSimpleName().toString() + "()";

        if ( Executables.isSetterMethod( targetAcessor ) ) {
            targetType = typeFactory.getSingleParameter( targetAcessor ).getType();
        }
        else if ( Executables.isGetterMethod( targetAcessor ) ) {
            targetType = typeFactory.getReturnType( targetAcessor );
        }

        MethodReference propertyMappingMethod = getMappingMethodReference(
            method,
            "property '" + Executables.getPropertyName( sourceAccessor ) + "'",
            mapperReferences,
            methods,
            sourceType,
            targetType
        );
        TypeConversion conversion = getConversion(
            sourceType,
            targetType,
            dateFormat,
            conversionString
        );

        PropertyMapping property = new PropertyMapping(
            parameter.getName(),
            Executables.getPropertyName( sourceAccessor ),
            sourceAccessor.getSimpleName().toString(),
            sourceType,
            Executables.getPropertyName( targetAcessor ),
            targetAcessor.getSimpleName().toString(),
            targetType,
            propertyMappingMethod,
            conversion
        );

        reportErrorIfPropertyCanNotBeMapped(
            method,
            property
        );

        return property;
    }