In JDK 8u40, javac dropped declaration annotations on lambda formals on the floor. Nothing in JLS8 suggested this treatment for such annotations, but it was a happy accident nonetheless -- according to Brian Goetz, there is no need to tie the synthetic method generated for a lambda expression back to the source lambda expression by carefully mapping the parameter annotations.

in JDK 9 (and presumably in JDK 8u60), javac preserves declaration annotations on lambda formals as Runtime[In]VisibleParameterAnnotations in the synthetic method. Similar to the names of the lambda formals, this preservation should not happen. The covering JLS change is specified in JDK-8140279.