sign pom only when uploading archives to sonatype

Author: mcweba

build.gradle

@@ -155,10 +155,9 @@ uploadArchives {
                 authentication(userName: "$repoUsername", password: "$repoPassword")
             }
 
-        if(uploadToMavenCentral) {
-            beforeDeployment { org.gradle.api.artifacts.maven.MavenDeployment deployment -> signing.signPom(deployment) }
-        }
-
+            if (project.property('uploadRepository').contains("sonatype")) {
+                beforeDeployment { org.gradle.api.artifacts.maven.MavenDeployment deployment -> signing.signPom(deployment) }
+            }
 
             configurePom(pom)
         }