public static DocumentId of(String serialized) {
        DocumentId parsed = parse(serialized);
        if (parsed != null) return parsed;
        throw new IllegalArgumentException("Document ID must be on the form " +
                                           "'id:<namespace>:<document-type>:[n=<number>|g=<group>]:<user-specific>', " +
                                           "but was '" + serialized + "'");
    }
Represents a Vespa document id

@author jonmv
vespa-feed-client-api/src/main/java/ai/vespa/feed/client/DocumentId.java