How do I suppress warnings when compiling an android library with gradle?

Question

In my application I have a library developed by a 3rd party that unfortunately contains quite a few lint and javac warnings. I'd like to ignore both these types of warnings since they can't be fixed by our team and they are polluting our build logs. I have tried adding the following to the libraries build.gradle file:

In the android block

lintOptions {
    ignoreWarnings = true
}

I also added the following to the end of the build.gradle file:

afterEvaluate {
    tasks.withType(JavaCompile) {
         it.options.compilerArgs << "-Xlint:none" << "-nowarn"
    }
}

Unfortunately, whenever ":compileDebugJavaWithJavac" runs, it still outputs the warnings from this project. What am I doing wrong?

EDIT Here is the build.gradle file in its entirety

apply plugin: 'com.android.library'

dependencies {
    compile fileTree(dir: 'libs', include: '*.jar')
}

android {
    compileSdkVersion 21
    buildToolsVersion "23.0.2"

    lintOptions {
       abortOnError false        // true by default
       checkAllWarnings false
       checkReleaseBuilds false
       ignoreWarnings true       // false by default
       quiet true                // false by default
    }

    sourceSets {
        main {
            manifest.srcFile 'AndroidManifest.xml'
            java.srcDirs = ['src']
            resources.srcDirs = ['src']
            aidl.srcDirs = ['src']
            renderscript.srcDirs = ['src']
            res.srcDirs = ['res']
            assets.srcDirs = ['assets']
        }

        // Move the tests to tests/java, tests/res, etc...
        instrumentTest.setRoot('tests')

        // Move the build types to build-types/<type>
        // For instance, build-types/debug/java, build-types/debug/AndroidManifest.xml, ...
        // This moves them out of them default location under src/<type>/... which would
        // conflict with src/ being used by the main source set.
        // Adding new build types or product flavors should be accompanied
        // by a similar customization.
        debug.setRoot('build-types/debug')
        release.setRoot('build-types/release')
    }
}

afterEvaluate {
    tasks.withType(JavaCompile) {
         it.options.compilerArgs << "-Xlint:none" << "-nowarn"
    }
}

The following is an example of the warnings I am getting that I want to eliminate:

warning: [unchecked] unchecked call to isAssignableFrom(Class) as a member of the raw type Class if (type.isAssignableFrom(throwables[i].getClass()))

Answer 1

Lint:

Docs: http://google.github.io/android-gradle-dsl/current/com.android.build.gradle.internal.dsl.LintOptions.html#com.android.build.gradle.internal.dsl.LintOptions:ignoreWarnings

android {
   lintOptions {
      abortOnError false        // true by default
      checkAllWarnings false
      checkReleaseBuilds false
      ignoreWarnings true       // false by default
      quiet true                // false by default
   }
}

Javac:

Docs: https://docs.oracle.com/javase/8/docs/technotes/tools/windows/javac.html

From the docs, list of all warnings:

Docs: https://docs.oracle.com/javase/8/docs/technotes/tools/windows/javac.html#BHCJCABJ

Java version:

$ java -version
java version "1.8.0_102"
Java(TM) SE Runtime Environment (build 1.8.0_102-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.102-b14, mixed mode)

Also, warning options:

$ javac -X
  -Xlint                     Enable recommended warnings
  -Xlint:{all,auxiliaryclass,cast,classfile,deprecation,dep-ann,divzero,empty,fallthrough,finally,options,overloads,overrides,path,processing,rawtypes,serial,static,try,unchecked,varargs,-auxiliaryclass,-cast,-classfile,-deprecation,-dep-ann,-divzero,-empty,-fallthrough,-finally,-options,-overloads,-overrides,-path,-processing,-rawtypes,-serial,-static,-try,-unchecked,-varargs,none} Enable or disable specific warnings
  -Xdoclint                  Enable recommended checks for problems in javadoc comments
  -Xdoclint:(all|none|[-]<group>)[/<access>] 
        Enable or disable specific checks for problems in javadoc comments,
        where <group> is one of accessibility, html, missing, reference, or syntax,
        and <access> is one of public, protected, package, or private.
  -Xbootclasspath/p:<path>   Prepend to the bootstrap class path
  -Xbootclasspath/a:<path>   Append to the bootstrap class path
  -Xbootclasspath:<path>     Override location of bootstrap class files
  -Djava.ext.dirs=<dirs>     Override location of installed extensions
  -Djava.endorsed.dirs=<dirs> Override location of endorsed standards path
  -Xmaxerrs <number>         Set the maximum number of errors to print
  -Xmaxwarns <number>        Set the maximum number of warnings to print
  -Xstdout <filename>        Redirect standard output
  -Xprint                    Print out a textual representation of specified types
  -XprintRounds              Print information about rounds of annotation processing
  -XprintProcessorInfo       Print information about which annotations a processor is asked to process
  -Xprefer:{source,newer}    Specify which file to read when both a source file and class file are found for an implicitly compiled class
  -Xpkginfo:{always,legacy,nonempty} Specify handling of package-info files
  -Xplugin:"name args"       Name and optional arguments for a plug-in to be run
  -Xdiags:{compact,verbose}  Select a diagnostic mode

These options are non-standard and subject to change without notice.

Turn all warnings off:

// Put this in 'root' `build.gradle`, in allprojects or subprojects
tasks.withType(JavaCompile) {
     // Try to turn them all off automatically
     options.compilerArgs << '-Xlint:none'
     options.compilerArgs << '-nowarn' // same as '-Xlint:none'

     // Turn them off manually
     options.compilerArgs << '-Xlint:-auxiliaryclass'
     options.compilerArgs << '-Xlint:-cast'
     options.compilerArgs << '-Xlint:-classfile'
     options.compilerArgs << '-Xlint:-deprecation'
     options.compilerArgs << '-Xlint:-dep-ann'
     options.compilerArgs << '-Xlint:-divzero'
     options.compilerArgs << '-Xlint:-empty'
     options.compilerArgs << '-Xlint:-fallthrough'
     options.compilerArgs << '-Xlint:-finally'
     options.compilerArgs << '-Xlint:-options'
     options.compilerArgs << '-Xlint:-overloads'
     options.compilerArgs << '-Xlint:-overrides'
     options.compilerArgs << '-Xlint:-path'
     options.compilerArgs << '-Xlint:-processing'
     options.compilerArgs << '-Xlint:-rawtypes'
     options.compilerArgs << '-Xlint:-serial'
     options.compilerArgs << '-Xlint:-static'
     options.compilerArgs << '-Xlint:-try'
     options.compilerArgs << '-Xlint:-unchecked'
     options.compilerArgs << '-Xlint:-varargs'
}