Fix IndexOutOfBoundsException with quoted parameters in JulParameterizedArguments (#274)

Escape special characters (backslashes and double quotes) in the format
string before passing it to JavaTemplate. Without escaping, format strings
containing quotes like "Log message \"{0}\"" resulted in invalid Java syntax
during template application.

Fixes #273

Co-authored-by: Claude Opus 4.5 <[email protected]>

Author: timtebeek

src/main/java/org/openrewrite/java/logging/slf4j/JulParameterizedArguments.java

@@ -62,6 +62,15 @@ public static boolean isStringLiteral(Expression expression) {
             return expression instanceof J.Literal && TypeUtils.isString(((J.Literal) expression).getType());
         }
 
+        /**
+         * Escapes special characters in a string so it can be safely used as content
+         * inside a Java string literal in a JavaTemplate.
+         */
+        private static String escapeForJavaStringLiteral(String s) {
+            // Order matters: escape backslashes first to avoid double-escaping
+            return s.replace("\\", "\\\\").replace("\"", "\\\"");
+        }
+
         private static @Nullable String getMethodIdentifier(Expression levelArgument) {
             String levelSimpleName = levelArgument instanceof J.FieldAccess ?
                     (((J.FieldAccess) levelArgument).getName().getSimpleName()) :
@@ -121,12 +130,13 @@ public J.MethodInvocation visitMethodInvocation(J.MethodInvocation method, Execu
                             .withType(((JavaType.Array) requireNonNull(newArray.getType())).withElemType(JavaType.ShallowClass.build("java.lang.Object")));
                 }
 
+                String slf4jFormatString = escapeForJavaStringLiteral(originalFormatString.replaceAll("\\{\\d*}", "{}"));
                 J.MethodInvocation updatedMi = JavaTemplate.builder(newName + "(\"#{}\",#{anyArray(Object)})")
                         .build()
                         .apply(
                                 getCursor(),
                                 method.getCoordinates().replaceMethod(),
-                                originalFormatString.replaceAll("\\{\\d*}", "{}"),
+                                slf4jFormatString,
                                 updatedStringFormatArgument
                         );
 

src/test/java/org/openrewrite/java/logging/slf4j/JulParameterizedArgumentsTest.java

@@ -16,6 +16,7 @@
 package org.openrewrite.java.logging.slf4j;
 
 import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 import org.openrewrite.DocumentExample;
 import org.openrewrite.Issue;
@@ -295,4 +296,65 @@ void method(Logger logger, Level level, String param1) {
           )
         );
     }
+
+    @Nested
+    @Issue("https://github.com/openrewrite/rewrite-logging-frameworks/issues/273")
+    class EscapedCharactersInFormatString {
+
+        @Test
+        void quotedParameters() {
+            rewriteRun(
+              // language=java
+              java(
+                """
+                  import java.util.logging.Level;
+                  import java.util.logging.Logger;
+
+                  class Test {
+                      void method(Logger logger, String param1) {
+                          logger.log(Level.SEVERE, "Log message with quoted parameter \\"{0}\\"", param1);
+                      }
+                  }
+                  """,
+                """
+                  import org.slf4j.Logger;
+
+                  class Test {
+                      void method(Logger logger, String param1) {
+                          logger.error("Log message with quoted parameter \\"{}\\"", param1);
+                      }
+                  }
+                  """
+              )
+            );
+        }
+
+        @Test
+        void backslashInFormatString() {
+            rewriteRun(
+              // language=java
+              java(
+                """
+                  import java.util.logging.Level;
+                  import java.util.logging.Logger;
+
+                  class Test {
+                      void method(Logger logger, String param1) {
+                          logger.log(Level.INFO, "Path: C:\\\\Users\\\\{0}", param1);
+                      }
+                  }
+                  """,
+                """
+                  import org.slf4j.Logger;
+
+                  class Test {
+                      void method(Logger logger, String param1) {
+                          logger.info("Path: C:\\\\Users\\\\{}", param1);
+                      }
+                  }
+                  """
+              )
+            );
+        }
+    }
 }