DataNucleus supports persistence to heterogeneous datastores and this plugin provides persistence to JSON.
'org.datanucleus:datanucleus-json:1.0.2'
<dependency>
<groupId>org.datanucleus</groupId>
<artifactId>datanucleus-json</artifactId>
<version>1.0.2</version>
</dependency>
<dependency org="org.datanucleus" name="datanucleus-json" rev="1.0.2"/>
"org.datanucleus", "datanucleus-json", "1.0.2"