public void add(Class<?> srcClass, Class<?> destClass, String mapId, ClassMap classMap) {
        ClassMap result = classMappings.put(keyFactory.createKey(srcClass, destClass, mapId), classMap);
        failOnDuplicate(result, classMap);
    }
Internal class that determines the appropriate class mapping to be used for
the source and destination object being mapped. Only intended for internal
use.
core/src/main/java/com/github/dozermapper/core/classmap/ClassMappings.java