com/googlecode/concurrenttrees/radix/node/NodeFactory

cqengine 2.1.0 is been used for addIndex feature however post upgrade Agile PLM java application , it throwing error "com/googlecode/concurrenttrees/radix/node/NodeFactory" and not doing comparison.
cqengine 2.1.0 supports which version of concurrent-trees.
Tried below combination but still not working.
all combination of cqengine 2.1.0 /3.6.0 with concurrent-trees 2.6.1/2.4.0