'JavaType' works !! I was trying to unmarshall (deserialize) a List in json String to ArrayList java Objects and was struggling to find a solution since days.
Below is the code that finally gave me solution. Code:

JsonMarshallerUnmarshaller<T> {
    T targetClass;

    public ArrayList<T> unmarshal(String jsonString) {
        ObjectMapper mapper = new ObjectMapper();

        AnnotationIntrospector introspector = new JacksonAnnotationIntrospector();
        mapper.getDeserializationConfig()
            .withAnnotationIntrospector(introspector);

        mapper.getSerializationConfig()
            .withAnnotationIntrospector(introspector);
        JavaType type = mapper.getTypeFactory().
            constructCollectionType(
                ArrayList.class, 
                targetclass.getClass());

        try {
            Class c1 = this.targetclass.getClass();
            Class c2 = this.targetclass1.getClass();
            ArrayList<T> temp = (ArrayList<T>) 
                mapper.readValue(jsonString,  type);
            return temp ;
        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null ;
    }  
}

One approach will be to define a Jackson JavaType representing a list of items of type clazz. You still need to have access to the class of the generic parameter at runtime. The usual approach is something like

<T> class XX { XX(Class<T> clazz, ...) ... } 

to pass the class of the generic parameter into the generic class at construction.

Upon access to the Class clazz variable you can construct a Jackson JavaType representing, for example, a list of items of class clazz with the following statement.

JavaType itemType = mapper.getTypeFactory().constructCollectionType(List.class, clazz);

I hope it helped. I am using this approach in my own code.