GH-1601 Polishing - avoiding breaking change

spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/AbstractExtendedBindingProperties.java

@@ -48,8 +48,6 @@ public abstract class AbstractExtendedBindingProperties<C, P, T extends BinderSp
 
 	private ConfigurableApplicationContext applicationContext = new GenericApplicationContext();
 
-	public abstract Map<String, T> getBindings();
-
 	public void setBindings(Map<String, T> bindings) {
 		this.bindings.putAll(bindings);
 	}

spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/ExtendedBindingProperties.java

@@ -16,6 +16,9 @@
 
 package org.springframework.cloud.stream.binder;
 
+import java.util.Collections;
+import java.util.Map;
+
 /**
  * Properties that extend the common binding properties for a particular binder
  * implementation.
@@ -32,6 +35,10 @@ public interface ExtendedBindingProperties<C, P> {
 
 	P getExtendedProducerProperties(String channelName);
 
+	default Map<String, ? extends Object> getBindings() {
+		return Collections.emptyMap();
+	}
+
 	/**
 	 * Extended binding properties can define a default prefix to place all the extended
 	 * common producer and consumer properties. For example, if the binder type is foo it