[java][switch completion] IDEA-270439 Code completion for pattern matching in switch

Reuse the SealedUtils#findSameFileInheritorsClasses method in order to eliminate the duplicating code and reduce the searching scope. Enable "return" when there is a lambda in a switch label

GitOrigin-RevId: 6e6dbcb8d9b1b16828fcdd29c1e59b2f47a71bb5

java/java-tests/testData/codeInsight/completion/normal/CompleteReturnInSwitch.java

@@ -0,0 +1,26 @@
+
+class Main {
+
+  private static interface Empty {
+    void f();
+  }
+
+  private Empty f(Object o) {
+    return switch (o) {
+      default -> () -> {
+        retu<caret>
+      };
+    };
+  }
+
+  private Empty g(Object o1, Object o2) {
+    return switch (o1) {
+      default -> () -> {
+        switch (o2) {
+          case null -> { retu<caret> }
+          case default -> { retu<caret> }
+        }
+      };
+    };
+  }
+}

java/java-tests/testData/codeInsight/completion/normal/CompleteReturnInSwitch_after.java

@@ -0,0 +1,26 @@
+
+class Main {
+
+  private static interface Empty {
+    void f();
+  }
+
+  private Empty f(Object o) {
+    return switch (o) {
+      default -> () -> {
+        return;<caret>
+      };
+    };
+  }
+
+  private Empty g(Object o1, Object o2) {
+    return switch (o1) {
+      default -> () -> {
+        switch (o2) {
+          case null -> { return;<caret> }
+          case default -> { return;<caret> }
+        }
+      };
+    };
+  }
+}

java/java-tests/testData/codeInsight/completion/normal/variants/CompletionSealedHierarchyExpr.java

@@ -5,8 +5,8 @@ class Main {
       <caret>
     }
   }
-}
 
-sealed interface Sealed permits Variant1, Variant2 { }
-final class Variant1 implements Sealed { }
-final class Variant2 implements Sealed { }
+  private static sealed interface Sealed permits Variant1, Variant2 { }
+  private static final class Variant1 implements Sealed { }
+  private static final class Variant2 implements Sealed { }
+}

java/java-tests/testData/codeInsight/completion/normal/variants/CompletionSealedHierarchyStmt.java

@@ -5,8 +5,8 @@ class Main {
       <caret>
     }
   }
-}
 
-sealed interface Sealed permits Variant1, Variant2 { }
-final class Variant1 implements Sealed { }
-final class Variant2 implements Sealed { }
+  private static sealed interface Sealed permits Variant1, Variant2 { }
+  private static final class Variant1 implements Sealed { }
+  private static final class Variant2 implements Sealed { }
+}