Make report format tests more reliable

This commit ensures that report format tests don't break when the
ordering of reported missing fields change.

Author: bclozel

spring-graphql/src/test/java/org/springframework/graphql/execution/SchemaMappingInspectorTests.java

@@ -534,11 +534,11 @@ void reportUnmappedField() {
 					""";
 			 SchemaReport report = inspectSchema(schema, BookController.class);
 			assertThatReport(report).hasUnmappedFieldCount(1).hasSkippedTypeCount(0);
-			 assertThat(report.toString()).isEqualTo("""
-					GraphQL schema inspection:
-						Unmapped fields: {Book=[missing]}
-						Unmapped registrations: {Book.fetcher=BookController#fetcher[1 args], Query.paginatedBooks=BookController#paginatedBooks[0 args], Query.bookObject=BookController#bookObject[1 args], Query.bookById=BookController#bookById[1 args]}
-						Skipped types: []""");
+			 assertThat(report.toString())
+					 .contains("GraphQL schema inspection:", "Unmapped fields: {Book=[missing]}", "Unmapped registrations:",
+							 "{Book.fetcher=BookController#fetcher[1 args]", " Query.paginatedBooks=BookController#paginatedBooks[0 args]",
+							 "Query.bookObject=BookController#bookObject[1 args]", "Query.bookById=BookController#bookById[1 args]",
+							 "Skipped types: []");
 		 }
 
 	}