String value;

        value = FessFunctions.maskEmail(null);
        assertEquals("", value);

        value = FessFunctions.maskEmail("");
        assertEquals("", value);

        value = FessFunctions.maskEmail("aaa bbb ccc");
        assertEquals("aaa bbb ccc", value);

        value = FessFunctions.maskEmail("******@****.***");
        assertEquals("******@****.***", value);

  </function>

  <function>
    <description>Mask e-mail address.</description>
    <name>maskEmail</name>
    <function-class>org.codelibs.fess.taglib.FessFunctions</function-class>
    <function-signature>java.lang.String maskEmail(java.lang.String)</function-signature>
    <example>${fe:maskEmail(doc.content_description)}</example>
  </function>

  <function>

                .map(user -> user.hasRoles(roles) || user.hasRoles(ComponentUtil.getFessConfig().getAuthenticationAdminRolesAsArray()))
                .orElse(false);
    }

    public static String maskEmail(final String value) {
        if (value == null) {
            return StringUtil.EMPTY;
        }
        return EMAIL_ADDRESS_PATTERN.matcher(value).replaceAll("******@****.***");
    }