The MVEL language plugin allows to have mvel as the language of scripts to execute.
'org.elasticsearch:elasticsearch-lang-mvel:1.4.0'
<dependency>
<groupId>org.elasticsearch</groupId>
<artifactId>elasticsearch-lang-mvel</artifactId>
<version>1.4.0</version>
</dependency>
<dependency org="org.elasticsearch" name="elasticsearch-lang-mvel" rev="1.4.0"/>
"org.elasticsearch", "elasticsearch-lang-mvel", "1.4.0"