Duplicate PluginClassLoader instances cause JDBC query failures

Multiple PluginClassLoader instances load the same JDBC plugin classes, causing ClassCastException when querying JDBC-connected databases (MySQL, PostgreSQL). The same class is loaded by different classloader instances, making them incompatible at runtime.

Upgrade to the latest Trino version as older versions (397, 462) exhibited this issue. Check for duplicate JDBC connector plugin installations in the plugin directory. Verify catalog configurations don't reference conflicting plugin paths. Review the plugins directory structure for duplicate connector JARs.