Java: warn on string template single line trailing whitespace (IDEA-331315)

GitOrigin-RevId: c3c1d5ef02d3086a2c8dbf29a9fea5b1d31d18d4

java/java-impl-inspections/src/com/intellij/codeInspection/TrailingWhitespacesInTextBlockInspection.java

@@ -47,7 +47,6 @@ public final class TrailingWhitespacesInTextBlockInspection extends AbstractBase
       private boolean checkTextBlock(@NotNull PsiElement textBlock, @NotNull String suffix) {
         String text = textBlock.getText();
         String[] lines = text.split("\n", -1);
-        if (lines.length < 2) return false;
         int indent = getIndent(textBlock);
         if (indent == -1) return false;
         int offset = 0;

java/java-tests/testData/inspection/trailingWhitespacesInTextBlock/StringTemplateOneLine.after.java

@@ -0,0 +1,7 @@
+class StringTemplateOneLine {
+
+  public void foo(String type) {
+    String s = STR."""
+            Hello \{type}""";
+  }
+}

java/java-tests/testData/inspection/trailingWhitespacesInTextBlock/StringTemplateOneLine.java

@@ -0,0 +1,7 @@
+class StringTemplateOneLine {
+
+  public void foo(String type) {
+    String s = STR."""
+            Hello \{type}<warning descr="Trailing whitespace characters inside text block"><caret>    </warning>""";
+  }
+}

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

@@ -22,6 +22,7 @@ public class TrailingWhitespacesInTextBlockInspectionTest extends LightJavaInspe
   public void testStringTemplate4Java21Preview() { doTestEscape(); }
   public void testStringTemplate5() { doTest(); }
   public void testStringTemplate6() { doTestAll(); }
+  public void testStringTemplateOneLine() { doTestAll(); }
   public void testTrailingSpaces() { doTestAll(); }
   public void testTrailingTabs() { doTestEscape(); }
   public void testWithBlankLines() { doTestAll(); }