private List<ResolvedType> resolveWrapperComponentType(MemberScope<?, ?> fieldOrMethod) {
        return this.isWrapperType(fieldOrMethod.getType())
                ? Collections.singletonList(fieldOrMethod.getTypeParameterFor(this.wrapperType, 0))
                : null;
    }
Determine the type of the item/component wrapped in the given wrapper type.

@param fieldOrMethod reference to the method/field
@return the wrapped component type (or null if it is not a targeted wrapper (sub) type)
jsonschema-generator/src/main/java/com/github/victools/jsonschema/generator/impl/module/FlattenedWrapperModule.java