Could not find property jni and source set 'main'

```
apply plugin: 'com.android.model.application'

model {
    android {
        compileSdkVersion = 21
        buildToolsVersion = "22.0.1"

        defaultConfig.with {
            applicationId = "com.example.native_activity"
            minSdkVersion.apiLevel = 9
            targetSdkVersion.apiLevel = 9
        }

        sourceSets.main {
            jni.srcDirs = [] // This prevents the auto generation of Android.mk
            jniLibs.srcDir = 'src/main/libs'
            // This is not necessary unless you have precompiled libraries in your project.
        }
    }

```

Here is the stacktrace:

```
Caused by: org.gradle.model.internal.core.ModelRuleExecutionException: Exception thrown while executing model rule: model.android
    at org.gradle.model.internal.registry.DefaultModelRegistry.fireMutation(DefaultModelRegistry.java:485)
    at org.gradle.model.internal.registry.DefaultModelRegistry.access$1500(DefaultModelRegistry.java:45)
    at org.gradle.model.internal.registry.DefaultModelRegistry$RunModelAction.apply(DefaultModelRegistry.java:1464)
    at org.gradle.model.internal.registry.DefaultModelRegistry.transitionTo(DefaultModelRegistry.java:341)
    at org.gradle.model.internal.registry.DefaultModelRegistry.transition(DefaultModelRegistry.java:419)
    at org.gradle.model.internal.registry.DefaultModelRegistry.atStateOrMaybeLater(DefaultModelRegistry.java:183)
    at org.gradle.model.internal.registry.DefaultModelRegistry.atStateOrLater(DefaultModelRegistry.java:175)
    at org.gradle.execution.TaskNameResolver.selfClose(TaskNameResolver.java:101)
    at org.gradle.execution.TaskNameResolver.selfClosedTasksNode(TaskNameResolver.java:114)
    ... 60 more
Caused by: org.gradle.api.internal.MissingMethodException: Could not find method main() for arguments [build_f1cmjkxjjzysskbrs6852ixyj$_run_closure1_closure2_closure7@8c09fa7] on SourceSet container.

```

I googled like mad for the last 2 hours...