Java: strip trailing whitespace from text-block string template end correctly (IDEA-354777)

GitOrigin-RevId: fa0266faeeaf63b04451b4f068550e22e2cdf8ee

java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiFragmentImpl.java

@@ -144,6 +144,10 @@ public final class PsiFragmentImpl extends LeafPsiElement implements PsiFragment
       }
       result.append(c);
     }
+    if (strip == indent) {
+      int end = result.length();
+      result.delete(end - indent, end);
+    }
     return result.toString();
   }
 

java/java-tests/testSrc/com/intellij/java/codeInspection/StringTemplateReverseMigrationInspectionTest.java

@@ -27,6 +27,24 @@ public class StringTemplateReverseMigrationInspectionTest extends LightJavaCodeI
                }
              }""");
   }
+  
+  public void testTrailingWhitespace() {
+    doTest("""
+             class TrailingWhitespace {
+               void foo(String name) {
+                   String s = STR.""\"<caret>
+                                        Hello \\{name}
+                                        ""\";
+               }
+             }
+             """, """
+             class TrailingWhitespace {
+               void foo(String name) {
+                   String s = "Hello " + name + "\\n";
+               }
+             }
+             """);
+  }
 
   public void testOverrideStringProcessor() {
     doTest("""