[JENKINS-43507] Tidy up GitHubSCMNavigator

pom.xml

@@ -91,7 +91,7 @@
        <dependency>
            <groupId>org.jenkins-ci.plugins</groupId>
            <artifactId>branch-api</artifactId>
            <version>2.0.11-20170615.161903-2</version>
            <version>2.0.11-20170616.163514-4</version>
            <scope>test</scope>
        </dependency>
        <dependency>

src/main/java/org/jenkinsci/plugins/github_branch_source/GitHubSCMBuilder.java

@@ -49,7 +49,6 @@
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.transport.RefSpec;
import org.jenkinsci.plugins.github.config.GitHubServerConfig;
import org.kohsuke.github.GitHub;

/**
 * Builds a {@link GitSCM} for {@link GitHubSCMSource}.
@@ -58,17 +57,37 @@
 */
public class GitHubSCMBuilder extends GitSCMBuilder<GitHubSCMBuilder> {

    /**
     * Singleton instance of {@link HttpsRepositoryUriResolver}.
     */
    private static final HttpsRepositoryUriResolver HTTPS = new HttpsRepositoryUriResolver();
    /**
     * Singleton instance of {@link SshRepositoryUriResolver}.
     */
    private static final SshRepositoryUriResolver SSH = new SshRepositoryUriResolver();
    /**
     * The context within which credentials should be resolved.
     */
    @CheckForNull
    private final SCMSourceOwner context;
    /**
     * The API URL
     */
    @NonNull
    private final String apiUri;
    /**
     * The repository owner.
     */
    @NonNull
    private final String repoOwner;
    /**
     * The repository name.
     */
    @NonNull
    private final String repository;
    /**
     * The definitive HTML user-facing URL of the repository (as provided by the GitHub API) if available.
     */
    @CheckForNull
    private final URL repositoryUrl;

@@ -105,14 +124,20 @@ public GitHubSCMBuilder(@NonNull GitHubSCMSource source,
        }
    }

    /**
     * Tries to guess the HTTPS URL of the Git repository.
     *
     * @param source the source.
     * @return the (possibly incorrect) best guess at the Git repository URL.
     */
    private static String guessRemote(GitHubSCMSource source) {
        String apiUri = StringUtils.removeEnd(source.getApiUri(), "/");
        if (StringUtils.isBlank(apiUri) || GitHubServerConfig.GITHUB_URL.equals(apiUri)) {
            apiUri = "https://github.com";
        } else {
            apiUri = StringUtils.removeEnd(apiUri, "/api/v3");
        }
        return  apiUri + "/" + source.getRepoOwner() + "/" + source.getRepository() + ".git";
        return apiUri + "/" + source.getRepoOwner() + "/" + source.getRepository() + ".git";
    }

    /**
@@ -189,7 +214,6 @@ public static RepositoryUriResolver uriResolver(@CheckForNull Item context, @Non
        }
    }


    /**
     * Updates the {@link GitSCMBuilder#withRemote(String)} based on the current {@link #head()} and
     * {@link #revision()}.