Beantwortung meines eigenen Beitrags hier. Hier sind die Einstellungen zum Konfigurieren des Poolings in Jetty
<New id="pDatasourcePool" class="org.eclipse.jetty.plus.jndi.Resource">
<Arg><Ref refid="wac"/></Arg>
<Arg>jdbc/projectds</Arg>
<Arg>
<Call class="oracle.ucp.jdbc.PoolDataSourceFactory" name="getPoolDataSource" >
<Set name="URL">jdbc:oracle:thin:xxx</Set>
<Set name="user">user</Set>
<Set name="password">ser_dev1</Set>
<Set name="minPoolSize">2</Set>
<Set name="maxPoolSize">10</Set>
<Set name="initialPoolSize">2</Set>
<Set name="connectionFactoryClassName">oracle.jdbc.replay.OracleDataSourceImpl</Set>
</Call>
</Arg>