Include Graph API on Eclipse JNoSQL

[otaviojava]

Include Graph API for Eclipse JNoSQL.

The goal is to have support for both Apache Tinkerpop and Neo4J.

Person person = new Person();
Book book = new Book();

Edge<Person, Book> edge = Edge.source(person)
        .label("READS")
        .target(book)
        .property("since", 2019)
        .property("format", "digital")
        .build();