* @param propertyKey The key of the property. (NotNull)
     * @return The value of found property. (NotNull: if not found, exception)
     * @throws ConfigPropertyNotFoundException When the property is not found.
     */
    String get(String propertyKey);

    /**
     * Is the property true?
     * @param propertyKey The key of the property which is boolean type. (NotNull)

     * @param propertyKey The key of the property. (NotNull)
     * @return The value of found property. (NotNull: if not found, exception)
     * @throws ConfigPropertyNotFoundException When the property is not found.
     */
    String get(String propertyKey);

    /**
     * Is the property true?
     * @param propertyKey The key of the property which is boolean type. (NotNull)

          <item index="13" class="java.lang.String" itemvalue="org.eclipse.jdt.annotation.NonNull" />
          <item index="14" class="java.lang.String" itemvalue="org.jetbrains.annotations.NotNull" />
          <item index="15" class="java.lang.String" itemvalue="org.jspecify.annotations.NonNull" />
          <item index="16" class="java.lang.String" itemvalue="android.annotation.NonNull" />
        </list>
      </value>

            <!--
                We prefer org.jspecify for nullability annotations.
            -->
            <property name="illegalClasses" value="org.jetbrains.annotations.Nullable,org.jetbrains.annotations.NotNull"/>
        </module>

        <!-- Naming -->
        <module name="ConstantName"/>
        <module name="LocalFinalVariableName"/>
        <module name="LocalVariableName"/>
        <module name="MemberName">

    public static final String LABELS_LOGIN_UPDATE = "{labels.login.update}";

    /**
     * Assert the property is not null.
     * @param property The value of the property. (NotNull)
     */
    protected void assertPropertyNotNull(String property) {
        if (property == null) {
            String msg = "The argument 'property' for message should not be null.";