GH-1255 - Fix path handling for KAPT usage with Maven.

In our KAPT support, the base folder detection now also accommodates Maven usage by looking for its default generated sources output path.

Author: odrotbohm

spring-modulith-apt/src/main/java/org/springframework/modulith/apt/SpringModulithProcessor.java

@@ -319,7 +319,12 @@ private static Path getAptOutputFolder(ProcessingEnvironment environment) {
 		var kapt = environment.getOptions().get("kapt.kotlin.generated");
 
 		if (kapt != null) {
-			return Path.of(kapt.substring(0, kapt.indexOf("/build/generated/source")));
+
+			// Strip Gradle or Maven suffixes
+			var index = kapt.indexOf("/build/generated/source");
+			index = index == -1 ? kapt.indexOf("/target/generated-sources") : index;
+
+			return Path.of(kapt.substring(0, index));
 		}
 
 		return Path.of(".");