I am using Gerrit Trigger plugin, which has GerritCause class which extends SCMTriggerCause. BUILD_CAUSE variable says "SCMTRIGGER" but the condition is not fulfilled.

I've checked the source code and the change is easy to fix. In CauseCondition class replace String causeClassName to Class<? extends Cause> causeClass and than change isCausedBy() method to something like this:

boolean isCausedBy(Cause cause) {
    return this.causeClass.isInstance(cause);
} 

It allows more plugins to be integrated with Run Conditon plugin without code interference.