Function is_java_keyword 

pub fn is_java_keyword(name: &str) -> bool

Java reserved words (plus the null/true/false literals, and _ — a reserved IDENTIFIER since Java 9: Alipay’s instant-run patch system names fields _, and javac rejects it with “underscores are not allowed here”): Kotlin emits methods and fields named default (Companion.default()) — no Java program can name them, so both ddc’s declarations and these call sites map them to _<name> identically (which turns _ into __). NOTE: these are MEMBER-level escapes — locals/fields/params MAY legally carry the restricted contextual type names below (rt.jar has var locals), so those live in their own predicate.