@Override
	public JavaFileObject getJavaFileForOutput(@Nonnull JavaFileManager.Location location, @Nonnull String name, @Nonnull JavaFileObject.Kind
			kind, FileObject sibling) {
		// Name should be like "com.example.MyClass$MyInner"
		String internal = name.replace('.', '/');
		VirtualJavaFileObject obj = unitMap.getFile(internal);

		// Unknown class, assumed to be an inner class.
		// Add it to the unit map, so it can be fetched.
		if (obj == null) {
			obj = new VirtualJavaFileObject(internal, null);
			unitMap.addFile(internal, obj);
		}
		return obj;
	}
@param unitMap
		Class input map.
@param virtualClasspath
		In-memory classpath.
@param fallback
		Fallback manager.
recaf-core/src/main/java/software/coley/recaf/services/compile/VirtualFileManager.java