Mod structure example doesn't work

[MaxiHuHe04]

When I try to build the example mod structure with gradle, I get

A problem occurred configuring root project 'rifttest'.
> Could not resolve all artifacts for configuration ':classpath'.
   > Could not resolve org.dimdev:ForgeGradle:2.3-SNAPSHOT.
     Required by:
         project :
      > Could not resolve org.dimdev:ForgeGradle:2.3-SNAPSHOT.
         > Unable to load Maven meta-data from https://www.dimdev.org/maven/org/dimdev/ForgeGradle/2.3-SNAPSHOT/maven-metadata.xml.
            > Could not get resource 'https://www.dimdev.org/maven/org/dimdev/ForgeGradle/2.3-SNAPSHOT/maven-metadata.xml'.
               > Could not GET 'https://www.dimdev.org/maven/org/dimdev/ForgeGradle/2.3-SNAPSHOT/maven-metadata.xml'.
                  > sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

CONFIGURE FAILED in 1s
Cause: unable to find valid certification path to requested target

[Runemoro]

Update your Java to at least 8u101, older versions don't have IdenTrust certificates used by dimdev.org.