We had an issue with a SpringBoot web app where we had the following error message when querying /manage/beans

Could not write JSON Attempted to serialize java.lang.Class Forgot to register a type adapter?

This was due to org.springframework.boot.actuate.beans.BeansEndpoint.BeanDescriptor having a java.lang.Class<?> attribute.

We fixed it by configuring our Gson bean this way :

    @Bean
    public static Gson gson() {
        return new GsonBuilder()
                ...
                .addSerializationExclusionStrategy(new ExclusionStrategy() {
                    @Override
                    public boolean shouldSkipField(FieldAttributes field) {
                        return field.getDeclaredType().getTypeName().equals("java.lang.Class<?>");
                    }
                    @Override
                    public boolean shouldSkipClass(Class<?> clazz) {
                        return false;
                    }
                })
                .create();
    }