Intermittent Connection Failures to Aurora Mysql with IAM auth

After upgrading from 2.4.4 to 2.5.4 or 2.6.2 we get intermittent connection errors. Here is a stack trace.
(C3P0PooledConnectionPoolManager[identityToken->2vto81ac17wm1bs1woznmz|22b53226]HelperThread#5) [BasicResourcePool] - com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@297463db – Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (60). Last acquisition attempt exception:
java.sql.SQLNonTransientConnectionException: Could not connect to address=(host=<<scrubbed>>)(port=3306)(type=master) : Client does not support authentication protocol requested by server. plugin type was = 'mysql_clear_password'
at org.mariadb.jdbc.internal.util.exceptions.ExceptionMapper.get(ExceptionMapper.java:241)
at org.mariadb.jdbc.internal.protocol.AbstractConnectProtocol.connectWithoutProxy(AbstractConnectProtocol.java:1243)
at org.mariadb.jdbc.internal.util.Utils.retrieveProxy(Utils.java:622)
at org.mariadb.jdbc.MariaDbConnection.newConnection(MariaDbConnection.java:142)
at org.mariadb.jdbc.Driver.connect(Driver.java:86)
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1176)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1163)
at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1908)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)
Caused by: java.sql.SQLException: Client does not support authentication protocol requested by server. plugin type was = 'mysql_clear_password'
at org.mariadb.jdbc.authentication.AuthenticationPluginLoader.get(AuthenticationPluginLoader.java:53)
at org.mariadb.jdbc.internal.protocol.AbstractConnectProtocol.authenticationHandler(AbstractConnectProtocol.java:685)
at org.mariadb.jdbc.internal.protocol.AbstractConnectProtocol.createConnection(AbstractConnectProtocol.java:507)
at org.mariadb.jdbc.internal.protocol.AbstractConnectProtocol.connectWithoutProxy(AbstractConnectProtocol.java:1238)
... 12 more