ES6 Map implementation that prevents entry mutation outside of explicit set() calls.
This is the default map implementation used by RxMap, so as to prevent iterative / query methods
from passing back raw object refs (which would allow the caller to bypass change detection by direct editing).
ES6 Map implementation that prevents entry mutation outside of explicit set() calls. This is the default map implementation used by RxMap, so as to prevent iterative / query methods from passing back raw object refs (which would allow the caller to bypass change detection by direct editing).