diff --git a/config/codenarc/codenarc.xml b/config/codenarc/codenarc.xml
index c66e63cd..f5021747 100644
--- a/config/codenarc/codenarc.xml
+++ b/config/codenarc/codenarc.xml
@@ -37,13 +37,16 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   <ruleset-ref path='rulesets/design.xml'>
     <exclude name="Instanceof"/>
     <exclude name="ImplementationAsType"/>
+    <exclude name="BuilderMethodWithSideEffects"/>
   </ruleset-ref>
   <ruleset-ref path='rulesets/dry.xml'>
     <exclude name="DuplicateStringLiteral"/>
     <exclude name="DuplicateNumberLiteral"/>
   </ruleset-ref>
   <ruleset-ref path='rulesets/exceptions.xml'/>
-  <ruleset-ref path='rulesets/formatting.xml'/>
+  <ruleset-ref path='rulesets/formatting.xml'>
+    <exclude name="Indentation"/>
+  </ruleset-ref>
   <ruleset-ref path='rulesets/generic.xml'/>
   <ruleset-ref path='rulesets/grails.xml'/>
   <ruleset-ref path='rulesets/groovyism.xml'/>
@@ -69,12 +72,14 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     <exclude name="CrapMetric"/>
     <exclude name="CyclomaticComplexity"/>
     <exclude name="NestedBlockDepth"/>
+    <exclude name="MethodCount"/>
   </ruleset-ref>
   <ruleset-ref path='rulesets/unused.xml'/>
   <ruleset-ref path='rulesets/unnecessary.xml'>
     <exclude name="UnnecessaryCollectCall"/>
     <exclude name="UnnecessaryGetter"/>
     <exclude name="UnnecessaryGString"/>
+    <exclude name="UnnecessarySetter"/>
     <exclude name="UnnecessaryPublicModifier"/>
     <exclude name="UnnecessaryReturnKeyword"/>
   </ruleset-ref>
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 92165eed..9d2dc020 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -2,4 +2,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.3-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.8-bin.zip
diff --git a/src/main/groovy/com/google/protobuf/gradle/ExecutableLocator.groovy b/src/main/groovy/com/google/protobuf/gradle/ExecutableLocator.groovy
index 9ceba257..218035c6 100644
--- a/src/main/groovy/com/google/protobuf/gradle/ExecutableLocator.groovy
+++ b/src/main/groovy/com/google/protobuf/gradle/ExecutableLocator.groovy
@@ -36,19 +36,19 @@ import org.gradle.api.Named
  * configured, the plugin should try to run the executable from system search
  * path.
  */
-public class ExecutableLocator implements Named {
+class ExecutableLocator implements Named {
 
   private final String name
 
   private String artifact
   private String path
 
-  public ExecutableLocator(String name) {
+  ExecutableLocator(String name) {
     this.name = name
   }
 
   @Override
-  public String getName() {
+  String getName() {
     return name
   }
 
@@ -56,7 +56,7 @@ public class ExecutableLocator implements Named {
    * Specifies an artifact spec for downloading the executable from
    * repositories. spec format: '<groupId>:<artifactId>:<version>'
    */
-  public setArtifact(String spec) {
+  void setArtifact(String spec) {
     this.artifact = spec
     this.path = null
   }
@@ -64,16 +64,16 @@ public class ExecutableLocator implements Named {
   /**
    * Specifies a local path.
    */
-  public setPath(String path) {
+  void setPath(String path) {
     this.path = path
     this.artifact = null
   }
 
-  public String getArtifact() {
+  String getArtifact() {
     return artifact
   }
 
-  public String getPath() {
+  String getPath() {
     return path
   }
 }
diff --git a/src/main/groovy/com/google/protobuf/gradle/GenerateProtoTask.groovy b/src/main/groovy/com/google/protobuf/gradle/GenerateProtoTask.groovy
index 856e0242..38825ff4 100644
--- a/src/main/groovy/com/google/protobuf/gradle/GenerateProtoTask.groovy
+++ b/src/main/groovy/com/google/protobuf/gradle/GenerateProtoTask.groovy
@@ -31,7 +31,6 @@ package com.google.protobuf.gradle
 
 import com.google.common.base.Preconditions
 import com.google.common.collect.ImmutableList
-import com.google.common.primitives.Ints
 
 import org.gradle.api.DefaultTask
 import org.gradle.api.GradleException
@@ -297,9 +296,8 @@ public class GenerateProtoTask extends DefaultTask {
   public boolean getIsTest() {
     if (Utils.isAndroidProject(project)) {
       return isTestVariant
-    } else {
-      return Utils.isTest(sourceSet.name)
     }
+    return Utils.isTest(sourceSet.name)
   }
 
   /**
@@ -337,7 +335,7 @@ public class GenerateProtoTask extends DefaultTask {
     /**
      * Set the output directory for this plugin, relative to {@link GenerateProtoTask#outputBaseDir}.
      */
-    public setOutputSubDir(String outputSubDir) {
+    void setOutputSubDir(String outputSubDir) {
       this.outputSubDir = outputSubDir
     }
 
@@ -476,7 +474,7 @@ public class GenerateProtoTask extends DefaultTask {
     List<List<String>> cmds = []
     if (!protoFiles.isEmpty()) {
       int baseCmdLength = baseCmd.sum { it.length() + CMD_ARGUMENT_EXTRA_LENGTH }
-      List<String> currentArgs = new ArrayList<String>()
+      List<String> currentArgs = []
       int currentArgsLength = 0
       for (File proto: protoFiles) {
         String protoFileName = proto
diff --git a/src/main/groovy/com/google/protobuf/gradle/ProtobufPlugin.groovy b/src/main/groovy/com/google/protobuf/gradle/ProtobufPlugin.groovy
index d78abb8d..1c5ce233 100644
--- a/src/main/groovy/com/google/protobuf/gradle/ProtobufPlugin.groovy
+++ b/src/main/groovy/com/google/protobuf/gradle/ProtobufPlugin.groovy
@@ -98,7 +98,6 @@ class ProtobufPlugin implements Plugin<Project> {
           if (wasApplied) {
             project.logger.warn('The com.google.protobuf plugin was already applied to the project: ' + project.path
                 + ' and will not be applied again after plugin: ' + prerequisitePlugin.id)
-
           } else {
             wasApplied = true
 
@@ -152,7 +151,7 @@ class ProtobufPlugin implements Plugin<Project> {
      * Creates a configuration if necessary for a source set so that the build
      * author can configure dependencies for it.
      */
-    private createConfiguration(String sourceSetName) {
+    private void  createConfiguration(String sourceSetName) {
       String configName = Utils.getConfigName(sourceSetName, 'protobuf')
       if (project.configurations.findByName(configName) == null) {
         project.configurations.create(configName) {
@@ -167,7 +166,7 @@ class ProtobufPlugin implements Plugin<Project> {
      * Adds the proto extension to all SourceSets, e.g., it creates
      * sourceSets.main.proto and sourceSets.test.proto.
      */
-    private addSourceSetExtensions() {
+    private void addSourceSetExtensions() {
       getSourceSets().all {  sourceSet ->
         sourceSet.extensions.create('proto', ProtobufSourceDirectorySet, sourceSet.name, fileResolver)
       }
@@ -191,7 +190,7 @@ class ProtobufPlugin implements Plugin<Project> {
     /**
      * Adds Protobuf-related tasks to the project.
      */
-    private addProtoTasks() {
+    private void addProtoTasks() {
       if (Utils.isAndroidProject(project)) {
         getNonTestVariants().each { variant ->
           addTasksForVariant(variant, false)
@@ -209,7 +208,7 @@ class ProtobufPlugin implements Plugin<Project> {
     /**
      * Creates Protobuf tasks for a sourceSet in a Java project.
      */
-    private addTasksForSourceSet(final SourceSet sourceSet) {
+    private void addTasksForSourceSet(final SourceSet sourceSet) {
       Task generateProtoTask = addGenerateProtoTask(sourceSet.name, [sourceSet])
       generateProtoTask.sourceSet = sourceSet
       generateProtoTask.doneInitializing()
@@ -235,7 +234,7 @@ class ProtobufPlugin implements Plugin<Project> {
     /**
      * Creates Protobuf tasks for a variant in an Android project.
      */
-    private addTasksForVariant(final Object variant, boolean isTestVariant) {
+    private void addTasksForVariant(final Object variant, boolean isTestVariant) {
       Task generateProtoTask = addGenerateProtoTask(variant.name, variant.sourceSets)
       generateProtoTask.setVariant(variant, isTestVariant)
       generateProtoTask.flavors = ImmutableList.copyOf(variant.productFlavors.collect { it.name } )
@@ -398,12 +397,12 @@ class ProtobufPlugin implements Plugin<Project> {
       }
     }
 
-    private static linkGenerateProtoTasksToTask(Task task, GenerateProtoTask genProtoTask) {
+    private static void linkGenerateProtoTasksToTask(Task task, GenerateProtoTask genProtoTask) {
       task.dependsOn(genProtoTask)
       task.source genProtoTask.getOutputSourceDirectorySet()
     }
 
-    private linkGenerateProtoTasksToTaskName(String compileTaskName, GenerateProtoTask genProtoTask) {
+    private void linkGenerateProtoTasksToTaskName(String compileTaskName, GenerateProtoTask genProtoTask) {
       Task compileTask = project.tasks.findByName(compileTaskName)
       if (compileTask != null) {
         linkGenerateProtoTasksToTask(compileTask, genProtoTask)
@@ -418,7 +417,7 @@ class ProtobufPlugin implements Plugin<Project> {
       }
     }
 
-    private linkGenerateProtoTasksToSourceCompile() {
+    private void linkGenerateProtoTasksToSourceCompile() {
       if (Utils.isAndroidProject(project)) {
         (getNonTestVariants() + project.android.testVariants).each { variant ->
           project.protobuf.generateProtoTasks.ofVariant(variant.name).each { GenerateProtoTask genProtoTask ->