Basic dependency injection annotation framework with Java

DependencyNotFoundException.java

public class DependencyNotFoundException extends Exception {
    public DependencyNotFoundException(String message) {
        super(message);
    }
}

Inject.java

/**
 * Apply to a field to fill the field with a registered dependency.
 * <p>
 * If the InjectionContext cannot find the dependency and optional is disabled it will throw an exception on register
 */
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Inject {
    boolean optional() default false;
}

InjectionContext.java

public class InjectionContext {
    private final Map<Class<?>, Object> instanceMap = new IdentityHashMap<>();

    public void registerDependency(Class<?> type, Object instance) {
        instanceMap.put(type, instance);
    }

    /**
     * Remove a dependency from the injection context. This will not affect already loaded objects
     *
     * @param type dependency type to remove
     */
    public void removeDependency(Class<?> type) {
        instanceMap.remove(type);
    }

    /**
     * Gets all Inject fields of an object and fills the contents
     */
    public void load(Object object) throws DependencyNotFoundException, IllegalAccessException {
        for (Field field : object.getClass().getDeclaredFields()) {
            if (!field.isAnnotationPresent(Inject.class)) continue;

            Object instance = instanceMap.get(field.getType());
            if (instance == null)
                if (!field.getAnnotation(Inject.class).optional())
                    throw new DependencyNotFoundException(String.format("Non optional field %s on class %s annotated with Inject could not find an instance",
                            field.getName(), object.getClass().getName()));

            field.setAccessible(true);
            field.set(object, instance);
        }
    }
}