[java-completion] IDEA-356400 Join lines adds \n outside text block literal

GitOrigin-RevId: 8afe6a733da77bb78e42feec646437af62400d23

java/java-impl/src/com/intellij/codeInsight/editorActions/TextBlockJoinLinesHandler.java

@@ -31,6 +31,7 @@ public final class TextBlockJoinLinesHandler implements JoinRawLinesHandlerDeleg
         !tokenType.equals(JavaTokenType.TEXT_BLOCK_TEMPLATE_MID)) {
       return CANNOT_JOIN;
     }
+    if (file.findElementAt(end) != token) return CANNOT_JOIN;
     TextRange tokenRange = token.getTextRange();
     int lineNumber = doc.getLineNumber(start);
     boolean atStartLine = (tokenType.equals(JavaTokenType.TEXT_BLOCK_LITERAL) || tokenType.equals(JavaTokenType.TEXT_BLOCK_TEMPLATE_BEGIN))

java/java-tests/testData/codeInsight/joinLines/JoinOutsideOfTextBlock.java

@@ -0,0 +1,7 @@
+class X {
+  void x() {
+    System.out.println("""
+                         some text"""<caret>
+    );
+  }
+}

java/java-tests/testData/codeInsight/joinLines/JoinOutsideOfTextBlock_after.java

@@ -0,0 +1,6 @@
+class X {
+  void x() {
+    System.out.println("""
+                         some text"""<caret>);
+  }
+}

java/java-tests/testSrc/com/intellij/java/codeInsight/JoinLinesTest.java

@@ -318,6 +318,7 @@ public class JoinLinesTest extends LightJavaCodeInsightTestCase {
   public void testJoinTextBlockSlashSAtTheEnd() {doTest();}
   public void testJoinStringTemplateBackSlash() {doTest();}
   public void testJoinStringTemplateBackSlash2() {doTest();}
+  public void testJoinOutsideOfTextBlock() { doTest(); }
 
   private void doTest() {
     doTest(".java");