diff --git a/spring-cloud-app-broker-core/src/main/java/org/springframework/cloud/appbroker/extensions/parameters/ParametersTransformer.java b/spring-cloud-app-broker-core/src/main/java/org/springframework/cloud/appbroker/extensions/parameters/ParametersTransformer.java
index c5c798d83..973da44ce 100644
--- a/spring-cloud-app-broker-core/src/main/java/org/springframework/cloud/appbroker/extensions/parameters/ParametersTransformer.java
+++ b/spring-cloud-app-broker-core/src/main/java/org/springframework/cloud/appbroker/extensions/parameters/ParametersTransformer.java
@@ -20,6 +20,10 @@
 
 import reactor.core.publisher.Mono;
 
+/**
+ * Mutates the provided backing type.
+ * Returned value is effectively ignored.
+ */
 @FunctionalInterface
 public interface ParametersTransformer<T> {