Migrate all remaining classes to Flogger

This is the next part of the migration to Flogger. This change migrates
all remaining classes Flogger. This means all classes in Gerrit core now
use Flogger.

During this migration we try to make the log statements more consistent:
- avoid string concatenation
- avoid usage of String.format(...)

The visibility of the slf4j library is restricted to plugins and jgit
now. This avoids that we accidentally add new dependencies to slf4j.

Change-Id: Ide573327315a15cde69b68b5f27934deeb790d37
Signed-off-by: Edwin Kempin <ekempin@google.com>

java/com/google/gerrit/gpg/PushCertificateChecker.java

@@ -21,6 +21,7 @@ import static com.google.gerrit.gpg.PublicKeyStore.keyIdToString;
 import static com.google.gerrit.gpg.PublicKeyStore.keyToString;
 
 import com.google.common.base.Joiner;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.common.GpgKeyInfo.Status;
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
@@ -38,12 +39,10 @@ import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.transport.PushCertificate;
 import org.eclipse.jgit.transport.PushCertificate.NonceStatus;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 /** Checker for push certificates. */
 public abstract class PushCertificateChecker {
-  private static final Logger log = LoggerFactory.getLogger(PushCertificateChecker.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
 
   public static class Result {
     private final PGPPublicKey key;
@@ -107,7 +106,7 @@ public abstract class PushCertificateChecker {
       }
     } catch (PGPException | IOException e) {
       String msg = "Internal error checking push certificate";
-      log.error(msg, e);
+      logger.atSevere().withCause(e).log(msg);
       results.add(CheckResult.bad(msg));
     }