Prefer explicit route to default

spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/BeanFactoryFunctionCatalogTests.java

@@ -54,6 +54,13 @@ public class BeanFactoryFunctionCatalogTests {
 		assertThat(foos.apply(Flux.just(2)).blockFirst()).isEqualTo("4");
 	}
 
+	@Test
+	public void lookupNonExistentConsumerWithEmptyName() {
+		processor.register(new FunctionRegistration<>(new Foos()).names("foos"));
+		Consumer<Flux<String>> foos = processor.lookupConsumer("");
+		assertThat(foos).isNull();
+	}
+
 	@Test
 	public void composeFunction() {
 		processor.register(new FunctionRegistration<>(new Foos()).names("foos"));