public @Nullable List<PsiElement> get(final @NotNull QualifiedName qualifiedName) {
    final SoftReference<List<PsiElement>> references = myCache.get(qualifiedName);
    if (references == null) {
      return null;
    }
    final List<PsiElement> elements = references.get();
    if(elements != null && ! elements.stream().allMatch(PsiElement::isValid)) {
      // At least one element is invalid
      return null;
    }
    return elements != null ? Collections.unmodifiableList(elements) : null;
  }
public @Nullable List<PsiElement> get(final @NotNull QualifiedName qualifiedName)