Prevent UseTextBlocks from dropping comments in concatenations (#985)

Skip text block conversion if any comments exist in the binary expression tree, since text blocks (single J.Literal nodes) have nowhere to preserve inline comments from the middle of concatenations.

Co-authored-by: Tim te Beek <tim@mac.home>

Author: timtebeek

src/main/java/org/openrewrite/java/migrate/lang/UseTextBlocks.java

@@ -100,6 +100,10 @@ public J visitBinary(J.Binary binary, ExecutionContext ctx) {
                     return binary; // Not super.visitBinary(binary, ctx) because we don't want to visit the children
                 }
 
+                if (containsComments(binary)) {
+                    return binary;
+                }
+
                 boolean flattenable = flatAdditiveStringLiterals(binary, stringLiterals, contentSb, concatenationSb);
                 if (!flattenable) {
                     return super.visitBinary(binary, ctx);
@@ -195,6 +199,18 @@ private boolean isEndsWithSpecialCharacters(String content) {
         });
     }
 
+    private static boolean containsComments(Expression expression) {
+        if (expression instanceof J.Binary) {
+            J.Binary b = (J.Binary) expression;
+            if (!b.getPrefix().getComments().isEmpty() ||
+                !b.getPadding().getOperator().getBefore().getComments().isEmpty()) {
+                return true;
+            }
+            return containsComments(b.getLeft()) || containsComments(b.getRight());
+        }
+        return expression instanceof J.Literal && !expression.getPrefix().getComments().isEmpty();
+    }
+
     private static boolean allLiterals(Expression exp) {
         return isRegularStringLiteral(exp) || exp instanceof J.Binary &&
                                               ((J.Binary) exp).getOperator() == J.Binary.Type.Addition &&

src/test/java/org/openrewrite/java/migrate/lang/UseTextBlocksTest.java

@@ -256,6 +256,37 @@ class Test {
         );
     }
 
+    @Test
+    void doNotDropLineComments() {
+        rewriteRun(
+          //language=java
+          java(
+            """
+              class Test {
+                  String query = "SELECT * FROM\\n" + // table query
+                          "my_table\\n" +
+                          "WHERE something = 1;";
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void doNotDropBlockComments() {
+        rewriteRun(
+          //language=java
+          java(
+            """
+              class Test {
+                  String query = "SELECT * FROM\\n" + /* table name */ "my_table\\n" +
+                          "WHERE something = 1;";
+              }
+              """
+          )
+        );
+    }
+
     @Test
     void preferNoChangeIfCarriageReturnInContent() {
         rewriteRun(