restrict anonym -> lambda: reject if return type would be changed (IDEA-154805)

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/anonymous2lambda/beforeCodeBlockLambda.java

@@ -1,4 +1,4 @@
-// "Replace with lambda" "true"
+// "Replace with lambda" "false"
 class A {
   {
     bar(new Throwabl<caret>eComputable<String, Exception>() {

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/anonymous2lambda/beforeFormalTypes.java

@@ -1,4 +1,4 @@
-// "Replace with lambda" "true"
+// "Replace with lambda" "false"
 import java.util.*;
 class Test2 {
 

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/anonymous2lambda/beforeNestedOverloads.java

@@ -0,0 +1,33 @@
+// "Replace with lambda" "false"
+
+import java.util.*;
+import java.util.function.Function;
+
+import static java.util.Collections.emptyList;
+
+class Ambiguous {
+  public void setRoots(List<String> roots) {}
+
+  public static <T> List<T> concat(Iterable<? extends Collection<T>> list) {
+    return new ArrayList<T>();
+  }
+
+  public static <T> List<T> concat(List<List<? extends T>> lists) {
+    return new ArrayList<T>();
+  }
+
+  public static <T,V> List<V> map(Collection<? extends T> iterable, Function<T, V> mapping) {
+    return emptyList();
+  }
+
+  public void anonymousToLambda(HashSet<String> modules) {
+    setRoots(Ambiguous.concat(Ambiguous.map(modules, new Function<String, List<String>>() {
+                                @Override
+                                public List<String> apply(String s) {
+                                  return null;
+                                }
+                              })
+    ));
+  }
+
+}