BasicResourcePool.this.unused.add(0, resc); NullPointerException

[xtb359]

[ThreadPoolAsynchronousRunner] {} (C3P0PooledConnectionPoolManager[identityToken->z8kfltb7l920rj9a0cyd|6b3c1f17]-HelperThread-#2) Thread[C3P0PooledConnectionPoolManager[identityToken->z8kfltb7l920rj9a0cyd|6b3c1f17]-HelperThread-#2,5,main] -- caught unexpected Exception while executing posted task.
java.lang.NullPointerException: null
at java.util.LinkedList.linkBefore(LinkedList.java:157) ~[?:1.8.0_202]
at java.util.LinkedList.add(LinkedList.java:512) ~[?:1.8.0_202]
at com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask.run(BasicResourcePool.java:1385) ~[c3p0-0.9.5.2.jar:0.9.5.2]
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696) [mchange-commons-java-0.2.15.jar:0.2.15]

Why did this error occur and how can it be resolved？

[xtb359]

The server architecture is aarch64， The c3p0 version is 0.9.5.2