Add findbugs to Gradle build

build.gradle

@@ -12,6 +12,7 @@ buildscript {
 apply plugin: 'android-sdk-manager'
 apply plugin: 'com.android.application'
 apply plugin: 'checkstyle'
+apply plugin: 'findbugs'
 
 repositories {
     jcenter()
@@ -106,11 +107,25 @@ task checkstyle(type: Checkstyle) {
     ignoreFailures = true
     configFile file("config/checkstyle/checkstyle.xml")
 
-    source 'src'
+    source = project.android.sourceSets.main.java.getSrcDirs() +
+            project.android.sourceSets.androidTest.java.getSrcDirs()
     include '**/*.java'
     classpath = files()
 }
 
+check.dependsOn 'findbugs'
+task findbugs(type: FindBugs, dependsOn: [':compileDebugJava', ':compileDebugTestJava']) {
+    ignoreFailures = true
+    classes = fileTree('build/intermediates/classes/debug/') +
+            fileTree('build/intermediates/classes/test/debug/')
+    source = project.android.sourceSets.main.java.getSrcDirs() +
+            project.android.sourceSets.androidTest.java.getSrcDirs()
+    classpath = files()
+    effort = 'max'
+    includeFilter = file("$rootProject.projectDir/config/findbugs/include_filter.xml")
+    excludeFilter = file("$rootProject.projectDir/config/findbugs/exclude_filter.xml")
+}
+
 if (project.hasProperty('keyAlias')) {
     android.signingConfigs.release.keyAlias = keyAlias
 }

config/findbugs/exclude_filter.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<FindBugsFilter>
+    <Match>
+        <Class name="~com\.fsck\.k9\.R.*" />
+    </Match>
+    <Match>
+        <Class name="~android\..*" />
+    </Match>
+</FindBugsFilter>

config/findbugs/include_filter.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<FindBugsFilter>
+    <Match>
+        <Package name="~com\.fsck\.k9.*" />
+    </Match>
+</FindBugsFilter>

tests-on-jvm/build.gradle

@@ -3,6 +3,7 @@ repositories {
 }
 
 apply plugin: 'java'
+apply plugin: 'findbugs'
 
 dependencies {
     testCompile project(':')
@@ -27,6 +28,15 @@ sourceSets {
     }
 }
 
+findbugs {
+    ignoreFailures = true
+    effort = 'max'
+    includeFilter = file("$rootProject.projectDir/config/findbugs/include_filter.xml")
+    excludeFilter = file("$rootProject.projectDir/config/findbugs/exclude_filter.xml")
+}
+
+check.dependsOn 'findbugsTest'
+
 test.dependsOn ':compileDebugJava'
 
 task wrapper(type: Wrapper) {