build: setup findbugs gradle plugin

sets up gradle plugin to run on CI and generate a HTML report (avoid failing the build for now)

.travis.yml

@@ -36,7 +36,7 @@ before_script:
   - while [[ `adb shell pm path android` == 'Error'* ]]; do sleep 2; done
   - adb shell input keyevent 82 &
 
-script: ./gradlew lint checkstyle createDebugCoverageReport coveralls
+script: ./gradlew lint checkstyle findbugs createDebugCoverageReport coveralls
 
 sudo: false
 

config/findbugs/filter.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<FindBugsFilter>
+  <Match>
+    <Class name="~.*\.R\$.*"/>
+  </Match>
+  <Match>
+    <Class name="~.*\.Manifest\$.*"/>
+  </Match>
+</FindBugsFilter>

sdk/build.gradle

@@ -3,6 +3,7 @@ apply plugin: 'com.getkeepsafe.dexcount'
 apply plugin: 'maven-publish'
 apply plugin: 'com.jfrog.bintray'
 apply plugin: 'com.github.kt3k.coveralls'
+apply plugin: 'findbugs'
 
 repositories {
     jcenter()
@@ -160,3 +161,27 @@ dexcount {
     orderByMethodCount = true
     verbose true
 }
+
+findbugs {
+    sourceSets = []
+    ignoreFailures = true // don't break the build for now
+}
+
+task findbugs(type: FindBugs, dependsOn: assemble) {
+
+    effort "max"
+    reportLevel "low"
+    pluginClasspath = project.configurations.findbugsPlugins
+    classes = fileTree('build/intermediates/classes/')
+    source = fileTree('src/')
+    classpath = files()
+
+    excludeFilter = file("../config/findbugs/filter.xml")
+
+    reports {
+        reports {
+            xml.enabled = false
+            html.enabled = true
+        }
+    }
+}