During plugin development time, it's possible that you need dependencies to another plugin or a spécific API. It's necessary to add dependencies, plugins et APIs, in pom.xml file plugin.
case in point :
Consider plugin need the Document plugin to work. It's necessary to add dependency following in pom.xml file :
...
<dependencies>
...
<dependency>
<groupId>fr.paris.lutece.plugins</groupId>
<artifactId>plugin-document</artifactId>
<version>1.9.0</version>
<type>lutece-plugin</type>
</dependency>
...
</dependencies>
...