Graph Database in Java (other than Neo4J)

Is there any open source graph database available other than Neo4J?

NOTE: Why not Neo4J?
Neo4J is opensource, but counts primitives (number of nodes,relationships & properties). If you are using it for commercial use. And does not have any straight forward information of pricing on official website. so there can be potential vendor lock-in (Although I have just started my company, and don't have budget to spent money on software anyway.) so It is out of option.

As RobV said, if your graphs can be represented in just about any custom format such as RDF or DOT language, you're in luck! Here's various options you have:

• RDF: Jena - Considered to be the de facto implementation of RDF for Java, however it has it's oddities such as heavy usage of Iterators.
• RDF: Protégé - If you don't use Jena (and even if you would) but would like to use RDF, Protégé is the tool for you. It's basically a really well done ontology editor which makes handling the graph data a breeze. It also uses a plugin hierarchy similar to Eclipse and there's loads of plugins available so you can plugin stuff like OWL ontologies easily.
• DOT: GraphViz - Another very popular tool, GraphViz can generate graphs from DOT language. Very powerful, a bit tricky to learn but also potentially all you need.

Of course if it fits your company's profile, you could develop your own and start selling it as a product.