AdminFaces - Failed to read artifact descriptor

Good morning,

I'm starting with Admin-Faces . By including dependency on the project (eclipse), I'm getting the error below:

  

org.eclipse.aether.resolution.ArtifactDescriptorException: Failed to   read artifact descriptor for org.omnifaces: omnifaces: jar: 2.1

In% w_that I put the following dependency:

<!-- https://mvnrepository.com/artifact/com.github.adminfaces/admin-template -->
<dependency>
    <groupId>com.github.adminfaces</groupId>
        <artifactId>admin-template</artifactId>
        <version>1.0.0-RC18</version>
</dependency>