Use gson to make JSON string in proxy log formatter

This is simpler than using fasterxml.jackson.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=224583713

gradle/core/build.gradle

@@ -79,9 +79,6 @@ dependencies {
   testImplementation project(':third_party')
 
   compile 'com.beust:jcommander:1.48'
-  maybeRuntime 'com.fasterxml.jackson.core:jackson-core:2.9.6'
-  maybeRuntime 'com.fasterxml.jackson.core:jackson-annotations:2.8.0'
-  maybeRuntime 'com.fasterxml.jackson.core:jackson-databind:2.8.5'
   compile 'com.google.api-client:google-api-client:1.22.0'
   maybeRuntime 'com.google.api-client:google-api-client-appengine:1.22.0'
   maybeRuntime 'com.google.api-client:google-api-client-jackson2:1.20.0'

gradle/proxy/build.gradle

@@ -45,9 +45,6 @@ task deployJar(type: Jar) {
 
 dependencies {
   compile 'com.beust:jcommander:1.48'
-  compile 'com.fasterxml.jackson.core:jackson-annotations:2.8.9'
-  compile 'com.fasterxml.jackson.core:jackson-core:2.9.6'
-  compile 'com.fasterxml.jackson.core:jackson-databind:2.8.9'
   compile 'com.google.api-client:google-api-client:1.27.0'
   compile 'com.google.api-client:google-api-client:1.27.0'
   compile 'com.google.apis:google-api-services-cloudkms:v1-rev12-1.22.0'
@@ -55,6 +52,7 @@ dependencies {
   compile 'com.google.apis:google-api-services-storage:v1-rev86-1.22.0'
   compile 'com.google.auto.value:auto-value-annotations:1.6.2'
   compile 'com.google.code.findbugs:jsr305:3.0.2'
+  compile 'com.google.code.gson:gson:2.8.5'
   compile 'com.google.dagger:dagger:2.15'
   compile 'com.google.flogger:flogger:0.1'
   compile 'com.google.guava:guava:27.0-jre'

java/google/registry/proxy/BUILD

@@ -19,7 +19,6 @@ java_library(
     ]),
     deps = [
         "//java/google/registry/util",
-        "//third_party/java/jackson2:jackson2-databind",
         "@com_beust_jcommander",
         "@com_google_api_client",
         "@com_google_apis_google_api_services_cloudkms",
@@ -27,6 +26,7 @@ java_library(
         "@com_google_apis_google_api_services_storage",
         "@com_google_auto_value",
         "@com_google_code_findbugs_jsr305",
+        "@com_google_code_gson",
         "@com_google_dagger",
         "@com_google_flogger",
         "@com_google_flogger_system_backend",

java/google/registry/proxy/GcpJsonFormatter.java

@@ -14,10 +14,8 @@
 
 package google.registry.proxy;
 
-import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.collect.ImmutableMap;
-import com.fasterxml.jackson.core.JsonProcessingException;
+import com.google.gson.Gson;
-import com.fasterxml.jackson.databind.ObjectMapper;
-import com.google.auto.value.AutoValue;
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.util.logging.Formatter;
@@ -41,75 +39,31 @@ import java.util.logging.LogRecord;
  */
 class GcpJsonFormatter extends Formatter {
 
-  private static final ObjectMapper MAPPER = new ObjectMapper();
+  /** JSON field that determines the log level. */
-
+  private static final String SEVERITY = "severity";
-  @Override
-  public String format(LogRecord record) {
-    try {
-      return MAPPER.writeValueAsString(LogEvent.create(record)) + "\n";
-    } catch (JsonProcessingException e) {
-      throw new RuntimeException(e);
-    }
-  }
-
-  @AutoValue
-  abstract static class LogEvent {
-
-    /** Field that determines the log level. */
-    @JsonProperty("severity")
-    abstract String severity();
 
   /**
-     * Field that stores the calling class and function when the log occurs.
+   * JSON field that stores the calling class and function when the log occurs.
    *
    * <p>This field is not used by Stackdriver, but it is useful and can be found when the log
    * entries are expanded
    */
-    @JsonProperty("source")
+  private static final String SOURCE = "source";
-    abstract String source();
 
-    /** Field that contains the content, this will show up as the main entry in a log. */
+  /** JSON field that contains the content, this will show up as the main entry in a log. */
-    @JsonProperty("message")
+  private static final String MESSAGE = "message";
-    abstract String message();
 
-    static LogEvent create(LogRecord record) {
+  private static final Gson gson = new Gson();
+
+  @Override
+  public String format(LogRecord record) {
     // Add an extra newline before the message. Stackdriver does not show newlines correctly, and
     // treats them as whitespace. If you want to see correctly formatted log message, expand the
     // log and look for the jsonPayload.message field. This newline makes sure that the entire
     // message starts on its own line, so that indentation within the message is correct.
 
     String message = "\n" + record.getMessage();
-      Level level = record.getLevel();
+    String severity = severityFor(record.getLevel());
-      // See
-      // https://github.com/GoogleCloudPlatform/google-cloud-java/blob/master/google-cloud-logging/src/main/java/com/google/cloud/logging/Severity.java
-      // on how {@code Level} is mapped to severity.
-      String severity;
-      switch (level.intValue()) {
-          // FINEST
-        case 300:
-          // FINER
-        case 400:
-          // FINE
-        case 500:
-          severity = "DEBUG";
-          break;
-          // CONFIG
-        case 700:
-          // INFO
-        case 800:
-          severity = "INFO";
-          break;
-          // WARNING
-        case 900:
-          severity = "WARNING";
-          break;
-          // SEVERE
-        case 1000:
-          severity = "ERROR";
-          break;
-        default:
-          severity = "DEFAULT";
-      }
 
     // The rest is mostly lifted from java.util.logging.SimpleFormatter.
     String stacktrace = "";
@@ -132,7 +86,42 @@ class GcpJsonFormatter extends Formatter {
       source = record.getLoggerName();
     }
 
-      return new AutoValue_GcpJsonFormatter_LogEvent(severity, source, message + stacktrace);
+    return gson.toJson(
+            ImmutableMap.of(SEVERITY, severity, SOURCE, source, MESSAGE, message + stacktrace))
+        + '\n';
+  }
+
+  /**
+   * Map {@link Level} to a severity string that Stackdriver understands.
+   *
+   * @see <a
+   *     href="https://github.com/googleapis/google-cloud-java/blob/master/google-cloud-clients/google-cloud-logging/src/main/java/com/google/cloud/logging/LoggingHandler.java#L325">{@code LoggingHandler}</a>
+   */
+  private static String severityFor(Level level) {
+    switch (level.intValue()) {
+        // FINEST
+      case 300:
+        return "DEBUG";
+        // FINER
+      case 400:
+        return "DEBUG";
+        // FINE
+      case 500:
+        return "DEBUG";
+        // CONFIG
+      case 700:
+        return "INFO";
+        // INFO
+      case 800:
+        return "INFO";
+        // WARNING
+      case 900:
+        return "WARNING";
+        // SEVERE
+      case 1000:
+        return "ERROR";
+      default:
+        return "DEFAULT";
     }
   }
 }