Make ListenableFuture compliant with Java 8 lambda

Make it possible to use a ListenableFuture with Java 8
lambda expressions, using a syntax like
listenableFuture.onSuccess(() -> ...).onFailure(() -> ...);

Issue: SPR-11820
I thought that we usually do add empty lines around the constructors.

https://github.com/spring-projects/spring-framework/blob/master/spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java#L185-L186