Make sure you have the forge Maven2 repository reference and dependency definition in the root pom.xml of your project.
<repositories>
<!-- SNIP -->
<repository>
<id>hippo-maven2-forge</id>
<name>Hippo Maven 2 Forge Repository</name>
<url>http://maven.onehippo.com/maven2-forge/</url>
</repository>
<!-- SNIP -->
</repositories>
<!-- SNIP -->
<dependencyManagement>
<!-- SNIP -->
<dependencies>
<!-- SNIP -->
<!-- NOTE: You should set a property named 'forge.exdocpickerbase.version' to a version of this plugin! -->
<dependency>
<groupId>org.onehippo.forge.exdocpickerbase</groupId>
<artifactId>exdocpickerbase-openui-field</artifactId>
<version>${forge.exdocpickerbase.version}</version>
</dependency>
<!-- SNIP -->
</dependencies>
<!-- SNIP -->
</dependencyManagement>
Add the following dependency in either cms-dependencies/pom.xml in Hippo CMS v13+ or cms/pom.xml in the earlier versions.
<dependencies>
<!-- SNIP -->
<dependency>
<groupId>org.onehippo.forge.exdocpickerbase</groupId>
<artifactId>exdocpickerbase-openui-field</artifactId>
</dependency>
<!-- SNIP -->
</dependencies>
Now, you're ready to use the plugin!