Added tests for class object and nested objects.

idea/testData/completion/injava/ClassObject.java

@@ -0,0 +1,7 @@
+public class Testing {
+    public static void test() {
+        mockLib.foo.LibClass.object$.<caret>
+    }
+}
+
+// EXIST: classObjectFun

idea/testData/completion/injava/Nested.java

@@ -0,0 +1,9 @@
+import mockLib.foo
+
+public class Testing {
+    public static void test() {
+        new LibClass.<caret>
+    }
+}
+
+// EXIST: LibClass.Nested

idea/testData/completion/injava/NestedObjectInstance.java

@@ -0,0 +1,7 @@
+public class Testing {
+    public static void test() {
+        mockLib.foo.LibClass.object.NestedObject.<caret>
+    }
+}
+
+// EXIST: instance$

idea/testData/completion/injava/mockLib/main.kt

@@ -3,6 +3,15 @@ package mockLib.foo
 public class LibClass {
     public fun foo() {
     }
+
+    class object {
+        fun classObjectFun() {
+        }
+
+        public object NestedObject
+    }
+
+    public class Nested
 }
 
 public trait LibTrait {