Stop running RecyclerView prefrech tests on pre API 21.

Bug: 31399375
Change-Id: I944bf4dd8317ca83840f8b805508c43a8b785d21
diff --git a/v7/recyclerview/tests/src/android/support/v7/widget/RecyclerViewBasicTest.java b/v7/recyclerview/tests/src/android/support/v7/widget/RecyclerViewBasicTest.java
index 936feb2..97f9b92 100644
--- a/v7/recyclerview/tests/src/android/support/v7/widget/RecyclerViewBasicTest.java
+++ b/v7/recyclerview/tests/src/android/support/v7/widget/RecyclerViewBasicTest.java
@@ -25,10 +25,12 @@
 import static org.junit.Assert.assertTrue;
 
 import android.content.Context;
+import android.os.Build;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.os.SystemClock;
 import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.SdkSuppress;
 import android.support.test.runner.AndroidJUnit4;
 import android.test.suitebuilder.annotation.SmallTest;
 import android.util.AttributeSet;
@@ -347,6 +349,7 @@
                 loggingView.getOnSavedInstanceCnt());
     }
 
+    @SdkSuppress(minSdkVersion = Build.VERSION_CODES.LOLLIPOP)
     @Test
     public void prefetchChangesCacheSize() {
         MockLayoutManager mlm = new MockLayoutManager() {
diff --git a/v7/recyclerview/tests/src/android/support/v7/widget/RecyclerViewPrefetchTest.java b/v7/recyclerview/tests/src/android/support/v7/widget/RecyclerViewPrefetchTest.java
index 6b817be..e397b6e 100644
--- a/v7/recyclerview/tests/src/android/support/v7/widget/RecyclerViewPrefetchTest.java
+++ b/v7/recyclerview/tests/src/android/support/v7/widget/RecyclerViewPrefetchTest.java
@@ -16,6 +16,11 @@
 
 package android.support.v7.widget;
 
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import android.os.Build;
+import android.support.test.filters.SdkSuppress;
 import android.support.test.runner.AndroidJUnit4;
 import android.test.suitebuilder.annotation.SmallTest;
 
@@ -26,10 +31,8 @@
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 
-import static org.hamcrest.CoreMatchers.is;
-import static org.hamcrest.MatcherAssert.assertThat;
-
 @SmallTest
+@SdkSuppress(minSdkVersion = Build.VERSION_CODES.LOLLIPOP)
 @RunWith(AndroidJUnit4.class)
 public class RecyclerViewPrefetchTest extends BaseRecyclerViewInstrumentationTest {
     private class PrefetchLayoutManager extends TestLayoutManager {