I'm seeing the same issue, but after applying the changes stated by the OP, I'm still getting the same error.
<target name="install.reporting.into.jboss7" depends="check.birt.as7" if="birt.download" >
<mkdir dir="${install.home}/birt"/>
<unzip src="${install.home}/lib/birt-runtime-${birt.version.as7}.zip"
dest="${install.home}/birt"/>
<copy todir="${install.home}/target/jbpm-gwt-console-server-war/WEB-INF/lib">
<fileset dir="${install.home}/birt/birt-runtime-${birt.version.as7}/ReportEngine/lib">
<include name="**/*.jar"/>
<exclude name="**/org.apache.commons.codec_1.3.0.v201101211617.jar"/>
</fileset>
</copy>
JDK 1.6_u30
jBPM 5.2.0 Final Full
RHEL 6.2 x86_64
le_roy