Include stub with exception when failing to parse as Java

Author: timtebeek

rewrite-java/src/main/java/org/openrewrite/java/internal/template/JavaTemplateParser.java

@@ -276,7 +276,7 @@ private JavaSourceFile compileTemplate(@Language("java") String stub) {
                 .findFirst()
                 .filter(JavaSourceFile.class::isInstance) // Filters out ParseErrors
                 .map(JavaSourceFile.class::cast)
-                .orElseThrow(() -> new IllegalArgumentException("Could not parse as Java"));
+                .orElseThrow(() -> new IllegalArgumentException("Could not parse as Java:\n" + stub));
     }
 
     /**