$ {coord：nominalTime（）}无法解决Oozie协调器作业中的nominal_time

Question

<coordinator-app name="tmpfile-processor" frequency="${coord:hours(1)}"
    start="${start}" end="${end}" timezone="America/Chicago" xmlns="uri:oozie:coordinator:0.4" xmlns:sla="uri:oozie:sla:0.2">
    <action>
            <workflow>
                    <app-path>${workflowAppUri}</app-path>
                    <configuration>
                            <property>
                                    <name>jobTracker</name>
                                    <value>${jobTracker}</value>
                            </property>
                            <property>
                                    <name>nameNode</name>
                                    <value>${nameNode}</value>
                            </property>
                            <property>
                                    <name>queueName</name>
                                    <value>${queueName}</value>
                            </property>
                    </configuration>
            </workflow>
            <sla:info>
                    <sla:nominal-time>${coord:nominalTime()}</sla:nominal-time>
                    <sla:should-start>${1 * MINUTES}</sla:should-start>
                    <sla:should-end>${1 * MINUTES}</sla:should-end>
                    <sla:max-duration>${1 * MINUTES}</sla:max-duration>
                    <sla:alert-events>start_miss,end_miss,duration_miss</sla:alert-events>
                    <sla:alert-contact>user@xxx.com</sla:alert-contact>
            </sla:info>
    </action>

错误：变量[nominal_time]无法解析

据我所知，函数coord：nominalTime（）应该根据开始时间和频率返回nominal_time。 xmlns标签版本或其他什么地方有什么问题吗？