title: Error: package android.hardware.camera2 does not exist OpenCV
body: <p>I'm trying to add the OpenCV module to a project, but I'm not able to solve some gradle issues. Here is my <code>app.gradle</code> file:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 17
      buildToolsVersion "23.0.2"
  
      defaultConfig {
          applicationId "com.sveder.cardboardpassthrough"
          minSdkVersion 8
          targetSdkVersion 21
      }
  
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
          }
      }
  }
  
  dependencies {
      compile 'com.android.support:support-v4:18.0.0'
      compile files('libs/cardboard.jar')
      compile project(':openCVLibrary')
  }
  </code></pre>
  
  <p>Here's the <code>build.gradle</code> file of the OpenCV (3.0) module:</p>
  
  <pre><code>apply plugin: 'com.android.library'
  
  android {
      compileSdkVersion 17
      buildToolsVersion "23.0.2"
  
  defaultConfig {
      minSdkVersion 8
      targetSdkVersion 21
  }
  
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
          }
      }
  }
  </code></pre>
  
  <p>As you can see, my app and OpenCV gradle files match, and yet whenever I try to build the project I have the error <code>error: package android.hardware.camera2</code> does not exist. What am I doing wrong?</p>
  
  <p>Thanks in advance.</p>