BpfMap.java - add requires S+ annotation

Since the first mainline eBPF code (for Tethering offload)
landed in Android S.

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ifb44a43a98e7f0ff4cd59017b47f64eff30ee715

staticlibs/device/com/android/net/module/util/BpfBitmap.java

@@ -16,9 +16,11 @@
 
 package com.android.net.module.util;
 
+import android.os.Build;
 import android.system.ErrnoException;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.RequiresApi;
 
  /**
  *
@@ -26,6 +28,7 @@ import androidx.annotation.NonNull;
  * array type with key->int and value->uint64_t defined in the bpf program.
  *
  */
+@RequiresApi(Build.VERSION_CODES.S)
 public class BpfBitmap {
     private BpfMap<Struct.S32, Struct.S64> mBpfMap;
 

staticlibs/device/com/android/net/module/util/BpfMap.java

@@ -18,12 +18,14 @@ package com.android.net.module.util;
 import static android.system.OsConstants.EEXIST;
 import static android.system.OsConstants.ENOENT;
 
+import android.os.Build;
 import android.os.ParcelFileDescriptor;
 import android.system.ErrnoException;
 import android.util.Pair;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
@@ -40,6 +42,7 @@ import java.util.concurrent.ConcurrentHashMap;
  * @param <K> the key of the map.
  * @param <V> the value of the map.
  */
+@RequiresApi(Build.VERSION_CODES.S)
 public class BpfMap<K extends Struct, V extends Struct> implements IBpfMap<K, V> {
     static {
         System.loadLibrary(JniUtil.getJniLibraryName(BpfMap.class.getPackage()));