@Override
    public DependencyNode getOrCreate(Class<?> clazz) {
        return getIfPresent(clazz)
            .orElseGet(() -> nodes.computeIfAbsent(clazz, DependencyNodeImpl::new));
    }
The default implementation of the {@link DependencyGraph} interface.

@author Emil Forslund
@since  1.0.0
common-parent/injector/src/main/java/com/speedment/common/injector/internal/dependency/DependencyGraphImpl.java