Noir::JavaCalleeExtractor::FileCallees
callees_in_method for many handlers of one parsed file. Each call
without decl_index: / method_index: walks the whole tree twice to
build them, so a class with N actions resolved one by one cost O(N²)
(Struts2, 4000 @Action methods: 36s under --ai-context). This
builds both on first use and reuses them. Only valid while the tree
root belongs to is alive — inside the parse_java block.