#vulnerable code 
                                public PandaMethodBuilder parameterTypes(ModuleLoader moduleLoader, String... parameterTypes) {
        ClassPrototype[] prototypes = new ClassPrototype[parameterTypes.length];

        for (int i = 0; i < prototypes.length; i++) {
            prototypes[i] = moduleLoader.forClass(parameterTypes[i]).get();
        }

        this.parameterTypes = prototypes;
        return this;
    } 
                            #location 5 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public PandaMethodBuilder parameterTypes(ModuleLoader moduleLoader, String... parameterTypes) {
        ClassPrototypeReference[] prototypes = new ClassPrototypeReference[parameterTypes.length];

        for (int i = 0; i < prototypes.length; i++) {
            prototypes[i] = moduleLoader.forClass(parameterTypes[i]);
        }

        this.parameterTypes = prototypes;
        return this;
    }