Hello,
bad copy/paste of my classpath
indeed log4j did the trick, here by my correct classpath initialisation :
#----------------------------------------------------------------------------------------------------------#
# POI 5.1.0 JAVA CLASSES :
https://www.apache.org/dyn/closer.lua/poi/release/bin/poi-bin-5.1.0-20211024.tgz# WITH POI 5.1 NEED ALSO
https://dlcdn.apache.org/logging/log4j/2.14.1/apache-log4j-2.14.1-bin.tar.gz#----------------------------------------------------------------------------------------------------------#
export POI_HOME=/opt/poi-5.1.0
export CLASSPATH=$POI_HOME/poi-5.1.0.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/poi-examples-5.1.0.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/poi-excelant-5.1.0.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/poi-javadoc-5.1.0.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/poi-ooxml-5.1.0.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/poi-ooxml-full-5.1.0.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/poi-ooxml-lite-5.1.0.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/poi-scratchpad-5.1.0.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/lib/commons-codec-1.15.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/lib/commons-collections4-4.4.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/lib/commons-io-2.11.0.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/lib/commons-math3-3.6.1.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/lib/log4j-api-2.14.1.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/lib/SparseBitSet-1.2.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/ooxml-lib/commons-compress-1.21.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/ooxml-lib/commons-logging-1.2.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/ooxml-lib/curvesapi-1.06.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/ooxml-lib/slf4j-api-1.7.32.jar
export CLASSPATH=$CLASSPATH:$POI_HOME/ooxml-lib/xmlbeans-5.0.2.jar
#----------------------------------------------------------------------------------------------------------#
# WITH POI 5.1 NEED ALSO
https://dlcdn.apache.org/logging/log4j/2.14.1/apache-log4j-2.14.1-bin.tar.gz#----------------------------------------------------------------------------------------------------------#
export CLASSPATH=$CLASSPATH:/opt/log4j-2.14.1/log4j-core-2.14.1.jar
Thank for your help