@Override
    public String toString() {
        return "LookupIdentifier{" +
                "key='" + key + '\'' +
                ", eventTime=" + eventTime +
                ", primaryMapName='" + primaryMapName + '\'' +
                ", secondaryMapName='" + secondaryMapName + '\'' +
                '}';
    }
@return The secondary map name which may itself be a nested map, e.g. "MAP2/MAP3"
stroom-pipeline/src/main/java/stroom/pipeline/refdata/LookupIdentifier.java