convert to stream: support nested conditions

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/afterNormalNestedFilters.java

@@ -0,0 +1,10 @@
+// "Replace with forEach" "true"
+import java.util.ArrayList;
+import java.util.List;
+
+class Sample {
+  List<String> foo = new ArrayList<>();
+  {
+      foo.stream().filter(s -> s != null).filter(s -> s.startsWith("a")).forEach(System.out::println);
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/beforeNormalNestedFilters.java

@@ -0,0 +1,16 @@
+// "Replace with forEach" "true"
+import java.util.ArrayList;
+import java.util.List;
+
+class Sample {
+  List<String> foo = new ArrayList<>();
+  {
+    for (String s : fo<caret>o) {
+      if (s != null) {
+        if (s.startsWith("a")) {
+          System.out.println(s);
+        }
+      }
+    }
+  }
+}