JoiningMigration: remove unnecessary side effect check for prefix: IDEA-207456

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/joining/afterJoiningPrefix.java

@@ -0,0 +1,12 @@
+// "Replace with collect" "true"
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class Test {
+  static String test(List<String> list) {
+    String sb = list.stream().filter(s -> !s.isEmpty()).map(String::trim).collect(Collectors.joining("", "asdsad" + "bar", ""));
+      //comment
+      return sb.length() == 0 ? null : sb;
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/joining/beforeJoiningPrefix.java

@@ -0,0 +1,17 @@
+// "Replace with collect" "true"
+
+import java.util.List;
+
+public class Test {
+  static String test(List<String> list) {
+    StringBuilder sb = new StringBuilder();
+    sb.append("asdsad").append("bar");
+    for(String s : li<caret>st) {
+      if(!s.isEmpty()) {
+        sb.append(s.trim());
+      }
+    }
+    return sb.length() == 0 ? null : sb.toString//comment
+      ();
+  }
+}