Fix a bug where leading whitespace was removed from the last line of a text block

If the last line contains contents other than the closing delimiter, it may have significant leading whitespace. This change prevents that whitespace from being removed.

#1195

PiperOrigin-RevId: 698939557

Author: cushon

core/src/main/java/com/google/googlejavaformat/java/StringWrapper.java

@@ -219,7 +219,7 @@ private void indentTextBlocks(
         StringBuilder output = new StringBuilder(initialLines.get(0).stripLeading());
         for (int i = 0; i < lines.size(); i++) {
           String line = lines.get(i);
-          String trimmed = line.stripLeading().stripTrailing();
+          String trimmed = line.stripTrailing();
           output.append(separator);
           if (!trimmed.isEmpty()) {
             // Don't add incidental leading whitespace to empty lines
@@ -228,7 +228,7 @@ private void indentTextBlocks(
           if (i == lines.size() - 1) {
             String withoutDelimiter =
                 trimmed.substring(0, trimmed.length() - TEXT_BLOCK_DELIMITER.length());
-            if (!withoutDelimiter.isEmpty()) {
+            if (!withoutDelimiter.stripLeading().isEmpty()) {
               output.append(withoutDelimiter).append('\\').append(separator).append(prefix);
             }
             // If the trailing line is just """, indenting it more than the prefix of incidental

core/src/test/java/com/google/googlejavaformat/java/FormatterIntegrationTest.java

@@ -57,7 +57,8 @@ public class FormatterIntegrationTest {
               "ExpressionSwitch",
               "I574",
               "I594",
-              "SwitchComment")
+              "SwitchComment",
+              "B380299722")
           .putAll(15, "I603")
           .putAll(16, "I588", "Sealed")
           .putAll(17, "I683", "I684", "I696")

core/src/test/resources/com/google/googlejavaformat/java/testdata/B380299722.input

@@ -0,0 +1,9 @@
+package com.helloworld;
+
+class Foo {
+  void foo() {
+    var bar = """
+        bar\
+         bar""";
+  }
+}

core/src/test/resources/com/google/googlejavaformat/java/testdata/B380299722.output

@@ -0,0 +1,11 @@
+package com.helloworld;
+
+class Foo {
+  void foo() {
+    var bar =
+        """
+        bar\
+         bar\
+        """;
+  }
+}