add injectFields method to InstanceContainer to inject fields for existing instance

src/yugecin/opsudance/core/inject/Injector.java

@@ -101,6 +101,11 @@ public abstract class Injector implements InstanceContainer, Binder {
 		return object;
 	}
 
+	@Override
+	public <T> T injectFields(T obj) {
+		return injectFields(obj, obj.getClass());
+	}
+
 	public final <T> Binder<T> bind(Class<T> type) {
 		lastType = type;
 		return this;

src/yugecin/opsudance/core/inject/InstanceContainer.java

@@ -20,5 +20,6 @@ package yugecin.opsudance.core.inject;
 public interface InstanceContainer {
 
 	<T> T provide(Class<T> type);
+	<T> T injectFields(T instance);
 
 }