Added test for the previously fixed NPE

spring-cloud-stream/src/main/java/org/springframework/cloud/stream/function/FunctionConfiguration.java

@@ -423,12 +423,11 @@ public class FunctionConfiguration {
 					.filter(clazz -> AnnotationUtils.findAnnotation(clazz, BindingProvider.class) != null)
 					.findFirst().isPresent();
 			if (!bindingProvider
-					&& ObjectUtils.isEmpty(applicationContext.getBeanNamesForAnnotation(EnableBinding.class))) {
-				this.determineFunctionName(functionCatalog, environment);
+					&& ObjectUtils.isEmpty(applicationContext.getBeanNamesForAnnotation(EnableBinding.class))
+					&& this.determineFunctionName(functionCatalog, environment)) {
 				BeanDefinitionRegistry registry = (BeanDefinitionRegistry) applicationContext.getBeanFactory();
 				RootBeanDefinition rootBeanDefinition = new RootBeanDefinition(BindableFunctionProxyFactory.class);
-				FunctionInvocationWrapper function = functionCatalog
-						.lookup(streamFunctionProperties.getDefinition());
+				FunctionInvocationWrapper function = functionCatalog.lookup(streamFunctionProperties.getDefinition());
 				if (function != null) {
 					if (function.isSupplier()) {
 						this.inputCount = 0;
@@ -447,7 +446,6 @@ public class FunctionConfiguration {
 					registry.registerBeanDefinition(streamFunctionProperties.getDefinition() + "_binding",
 							rootBeanDefinition);
 				}
-
 			}
 		}
 
@@ -459,7 +457,7 @@ public class FunctionConfiguration {
 			return this.outputCount;
 		}
 
-		private void determineFunctionName(FunctionCatalog catalog, Environment environment) {
+		private boolean determineFunctionName(FunctionCatalog catalog, Environment environment) {
 			String definition = streamFunctionProperties.getDefinition();
 			if (!StringUtils.hasText(definition)) {
 				definition = environment.getProperty("spring.cloud.function.definition");
@@ -474,6 +472,7 @@ public class FunctionConfiguration {
 			else {
 				streamFunctionProperties.setDefinition(((FunctionInspector) functionCatalog).getName(functionCatalog.lookup("")));
 			}
+			return StringUtils.hasText(streamFunctionProperties.getDefinition());
 		}
 
 		@Override

spring-cloud-stream/src/main/java/org/springframework/cloud/stream/function/StreamFunctionProperties.java

@@ -73,13 +73,12 @@ public class StreamFunctionProperties {
 	}
 
 	public void setDefinition(String definition) {
-		if (definition == null) {
-			return;
+		if (StringUtils.hasText(definition)) {
+			this.composeFrom = definition.startsWith("|");
+			this.composeTo = definition.endsWith("|");
+			this.definition = this.composeFrom ? definition.substring(1)
+					: (this.composeTo ? definition.substring(0, definition.length() - 1) : definition);
 		}
-		this.composeFrom = definition.startsWith("|");
-		this.composeTo = definition.endsWith("|");
-		this.definition = this.composeFrom ? definition.substring(1)
-				: (this.composeTo ? definition.substring(0, definition.length() - 1) : definition);
 	}
 
 	BindingServiceProperties getBindingServiceProperties() {

spring-cloud-stream/src/test/java/org/springframework/cloud/stream/function/ImplicitFunctionBindingTests.java

@@ -39,6 +39,7 @@ import org.springframework.messaging.Message;
 import org.springframework.messaging.support.GenericMessage;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.fail;
 
 /**
  *
@@ -53,6 +54,21 @@ public class ImplicitFunctionBindingTests {
 		System.clearProperty("spring.cloud.function.definition");
 	}
 
+	@Test
+	public void testEmptyConfiguration() {
+
+		try (ConfigurableApplicationContext context = new SpringApplicationBuilder(
+				TestChannelBinderConfiguration.getCompleteConfiguration(
+						EmptyConfiguration.class))
+								.web(WebApplicationType.NONE)
+								.run("--spring.jmx.enabled=false")) {
+			context.getBean(InputDestination.class);
+		}
+		catch (Exception e) { // should not fail
+			fail();
+		}
+	}
+
 	@Test
 	public void testSimpleFunctionWithStreamProperty() {
 
@@ -291,4 +307,9 @@ public class ImplicitFunctionBindingTests {
 		}
 	}
 
+	@EnableAutoConfiguration
+	public static class EmptyConfiguration {
+
+	}
+
 }