A "NullPointerException" could be thrown; "getListenerContainer()" can return null.

private final KafkaListenerEndpointRegistry registry;

public void register() {
        try {
            registry.getListenerContainer(LicenseEventSubscriber.ID).start();
        } catch (Exception e) {
            log.error("registry load failed.", e);
        }
    }

[Null pointers should not be dereferenced]

A reference to null should never be dereferenced/accessed. 
Doing so will cause a NullPointerException to be thrown. 
At best, such an exception will cause abrupt program termination. 
At worst, it could expose debugging information that would be useful to an attacker, 
or it could allow an attacker to bypass security measures.

Note that when they are present, 
this rule takes advantage of @CheckForNull and @Nonnull annotations 
defined in JSR-305 to understand 
which values are and are not nullable except 
when @Nonnull is used on the parameter to equals, 
which by contract should always work with null.