private static Integer getJdkClassProximity(@Nullable PsiClass element) {
    String qname = element == null ? null : element.getQualifiedName();
    if (qname == null) return null;
    
    if (isDispreferredName(qname)) return -1;

    if (element.getContainingClass() != null) return 0;
    
    String pkg = StringUtil.getPackageName(qname);
    if (qname.equals(JAVA_LANG_OBJECT)) return 5;
    if (POPULAR_JDK_CLASSES.contains(qname)) return 8;
    if (pkg.equals("java.lang")) return 6;
    if (pkg.equals("java.util")) return 7;

    if (qname.startsWith("java.lang")) return 5;
    if (qname.startsWith("java.util")) return 4;

    if (pkg.equals("javax.swing")) return 3;
    if (qname.startsWith("java.")) return 2;
    if (qname.startsWith("javax.")) return 1;
    return 0;
  }
private static Integer getJdkClassProximity(@Nullable PsiClass element)