Fuse ログに ”ERRORCODE=-4470、SQLSTATE=08003 DB2 Connection is closed” エラーが表示されるのはなぜですか?

Issue

• 実稼働環境のログに以下の (添付の) 例外が表示されるのはなぜですか?

Caused by: com.ibm.db2.jcc.am.SqlNonTransientConnectionException: [jcc][t4][10335][10366][4.15.82] Invalid operation: Connection is closed. ERRORCODE=-4470, SQLSTATE=08003
    at com.ibm.db2.jcc.am.fd.a(fd.java:686)[277:wrap_mvn_com.ibm_db2jcc4_4.15.82:0

• 以下はデータソースの設定です。

    <service interface="javax.sql.DataSource">
        <service-properties>
            <entry key="osgi.jndi.service.name" value="jdbc/DataSource" />
        </service-properties>
        <bean class="com.ibm.db2.jcc.DB2DataSource">
            <property name="serverName" value="${db.connection.host}" />
            <property name="portNumber" value="${db.connection.port}" />
            <property name="databaseName" value="${db.connection.sid}" />
            <property name="currentSchema" value="${db.connection.currentSchema}" />
            <property name="user" value="${db.connection.user}" />
            <property name="password" value="${db.connection.password}" />
            <property name="driverType" value="4" />
            <property name="dataSourceName" value="TestConnectionPoll" />
            <property name="blockingReadConnectionTimeout" value="15" />
            <property name="loginTimeout" value="3" />
        </bean>
    </service>

• 永続ユニットの設定は次のとおりです。

    <persistence-unit name="dmsPersistenceUnit" transaction-type="RESOURCE_LOCAL">
        <description>Persistence unit for the Test service</description>
        <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
        <non-jta-data-source>osgi:service/javax.sql.DataSource/(osgi.jndi.service.name=jdbc/DataSource)</non-jta-data-source>
        <class>test.TestEntity</class>
        <exclude-unlisted-classes>true</exclude-unlisted-classes>
        <properties>
            <property name="openjpa.jdbc.DBDictionary" value="db2" />
            <property name="openjpa.Log" value="DefaultLevel=WARN, Runtime=WARN, Tool=WARN, SQL=TRACE" />
            <property name="openjpa.ConnectionFactoryProperties" value="PrintParameters=true" />
            <!-- <property name="openjpa.DataCache" value="true(CacheSize=2000, SoftReferenceSize=2000)"/>
            <property name="openjpa.QueryCache" value="true"/> -->
        </properties>
    </persistence-unit>