proxy creates Java 1.5 bytecode
proxy generates classes and sets the bytecode version to Java 1.5 (other bytecode generation all uses Java 1.8 since Clojure 1.10).
We missed updating this in earlier JVM version updates (see similar code in gen-class, Compiler, etc).
Proposed: Use V1_8 to match all other class writer versions. Need to set the proper ClassWriter options, so use the (now standardized) Compiler.classWriter() function to construct the ClassWriter.
Screened by: Fogus
Released in 1.10.2-rc2
Viewed, reasoned about, applied, and tested patch.