Upgrade Flogger to 0.6

Change-Id: I8b1fdeefe77cca7677e72960fdb30a0a191716b1
diff --git a/java/com/google/gerrit/server/logging/LoggingContext.java b/java/com/google/gerrit/server/logging/LoggingContext.java
index 5611d08..3907da5 100644
--- a/java/com/google/gerrit/server/logging/LoggingContext.java
+++ b/java/com/google/gerrit/server/logging/LoggingContext.java
@@ -19,7 +19,7 @@
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSetMultimap;
-import com.google.common.flogger.backend.Tags;
+import com.google.common.flogger.context.Tags;
 import com.google.inject.Provider;
 import java.util.List;
 import java.util.concurrent.Callable;
diff --git a/java/com/google/gerrit/server/logging/MutableTags.java b/java/com/google/gerrit/server/logging/MutableTags.java
index 83009a6..3f48b59 100644
--- a/java/com/google/gerrit/server/logging/MutableTags.java
+++ b/java/com/google/gerrit/server/logging/MutableTags.java
@@ -20,7 +20,7 @@
 import com.google.common.collect.ImmutableSetMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.SetMultimap;
-import com.google.common.flogger.backend.Tags;
+import com.google.common.flogger.context.Tags;
 
 public class MutableTags {
   private final SetMultimap<String, String> tagMap =
diff --git a/tools/nongoogle.bzl b/tools/nongoogle.bzl
index e908f59..b1ebb5c 100644
--- a/tools/nongoogle.bzl
+++ b/tools/nongoogle.bzl
@@ -121,24 +121,24 @@
     # Google internal dependencies: these are developed at Google, so there is
     # no concern about version skew.
 
-    FLOGGER_VERS = "0.5.1"
+    FLOGGER_VERS = "0.6"
 
     maven_jar(
         name = "flogger",
         artifact = "com.google.flogger:flogger:" + FLOGGER_VERS,
-        sha1 = "71d1e2cef9cc604800825583df56b8ef5c053f14",
+        sha1 = "155dc6e303a58f7bbff5d2cd1a259de86827f4fe",
     )
 
     maven_jar(
         name = "flogger-log4j-backend",
         artifact = "com.google.flogger:flogger-log4j-backend:" + FLOGGER_VERS,
-        sha1 = "5e2794b75c88223f263f1c1a9d7ea51e2dc45732",
+        sha1 = "9743841bf10309163effd8ddf882b5d5190cc9d9",
     )
 
     maven_jar(
         name = "flogger-system-backend",
         artifact = "com.google.flogger:flogger-system-backend:" + FLOGGER_VERS,
-        sha1 = "b66d3bedb14da604828a8693bb24fd78e36b0e9e",
+        sha1 = "0f0ccf8923c6c315f2f57b108bcc6e46ccd88777",
     )
 
     maven_jar(