@Override
    public boolean equals(final Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        final LookupIdentifier that = (LookupIdentifier) o;
        return eventTime == that.eventTime &&
                Objects.equals(map, that.map) &&
                Objects.equals(key, that.key);
    }
@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