patch: Use simpler delegate for system reader

As suggested by @xenoterracide in #407, JGit now has a
SystemReader.Delegate which is an easier way to manage implementing
SystemReader. This protects us from new methods being added to
SystemReader, which otherwise would have caused a compile error.

Fixes #407

grgit-core/src/main/groovy/org/ajoberstar/grgit/auth/GrgitSystemReader.java

@@ -4,126 +4,35 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.text.DateFormat;
-import java.text.SimpleDateFormat;
-import java.util.*;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
 import java.util.function.Function;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import org.eclipse.jgit.errors.CorruptObjectException;
-import org.eclipse.jgit.lib.Config;
-import org.eclipse.jgit.storage.file.FileBasedConfig;
-import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.SystemReader;
-import org.eclipse.jgit.util.time.MonotonicClock;
 
-public class GrgitSystemReader extends SystemReader {
+public class GrgitSystemReader extends SystemReader.Delegate {
   private static final Pattern PATH_SPLITTER = Pattern.compile(Pattern.quote(File.pathSeparator));
-  private final SystemReader delegate;
   private final String gitSsh;
 
   public GrgitSystemReader(SystemReader delegate, String gitSsh) {
-    this.delegate = delegate;
+    super(delegate);
     this.gitSsh = gitSsh;
   }
 
-  @Override
-  public String getHostname() {
-    return delegate.getHostname();
-  }
-
   @Override
   public String getenv(String variable) {
-    String value = delegate.getenv(variable);
+    String value = super.getenv(variable);
     if ("GIT_SSH".equals(variable) && value == null) {
       return gitSsh;
     } else {
       return value;
     }
   }
 
-  @Override
-  public String getProperty(String key) {
-    return delegate.getProperty(key);
-  }
-
-  @Override
-  public FileBasedConfig openJGitConfig(Config parent, FS fs) {
-    return delegate.openJGitConfig(parent, fs);
-  }
-
-  @Override
-  public FileBasedConfig openUserConfig(Config parent, FS fs) {
-    return delegate.openUserConfig(parent, fs);
-  }
-
-  @Override
-  public FileBasedConfig openSystemConfig(Config parent, FS fs) {
-    return delegate.openSystemConfig(parent, fs);
-  }
-
-  @Override
-  public long getCurrentTime() {
-    return delegate.getCurrentTime();
-  }
-
-  @Override
-  public MonotonicClock getClock() {
-    return delegate.getClock();
-  }
-
-  @Override
-  public int getTimezone(long when) {
-    return delegate.getTimezone(when);
-  }
-
-  @Override
-  public TimeZone getTimeZone() {
-    return delegate.getTimeZone();
-  }
-
-  @Override
-  public Locale getLocale() {
-    return delegate.getLocale();
-  }
-
-  @Override
-  public SimpleDateFormat getSimpleDateFormat(String pattern) {
-    return delegate.getSimpleDateFormat(pattern);
-  }
-
-  @Override
-  public SimpleDateFormat getSimpleDateFormat(String pattern, Locale locale) {
-    return delegate.getSimpleDateFormat(pattern, locale);
-  }
-
-  @Override
-  public DateFormat getDateTimeInstance(int dateStyle, int timeStyle) {
-    return delegate.getDateTimeInstance(dateStyle, timeStyle);
-  }
-
-  @Override
-  public boolean isWindows() {
-    return delegate.isWindows();
-  }
-
-  @Override
-  public boolean isMacOS() {
-    return delegate.isWindows();
-  }
-
-  @Override
-  public void checkPath(String path) throws CorruptObjectException {
-    delegate.checkPath(path);
-  }
-
-  @Override
-  public void checkPath(byte[] path) throws CorruptObjectException {
-    delegate.checkPath(path);
-  }
-
   public static void install() {
     SystemReader current = SystemReader.getInstance();