diff --git a/staticlibs/devicetests/com/android/testutils/HandlerUtils.kt b/staticlibs/devicetests/com/android/testutils/HandlerUtils.kt
index fa36209..336e12c 100644
--- a/staticlibs/devicetests/com/android/testutils/HandlerUtils.kt
+++ b/staticlibs/devicetests/com/android/testutils/HandlerUtils.kt
@@ -20,7 +20,6 @@
 import android.os.Handler
 import android.os.HandlerThread
 import java.util.concurrent.Executor
-import kotlin.system.measureTimeMillis
 import kotlin.test.fail
 
 /**
diff --git a/staticlibs/devicetests/com/android/testutils/TapPacketReader.java b/staticlibs/devicetests/com/android/testutils/TapPacketReader.java
index fea1cd9..c36f144 100644
--- a/staticlibs/devicetests/com/android/testutils/TapPacketReader.java
+++ b/staticlibs/devicetests/com/android/testutils/TapPacketReader.java
@@ -34,6 +34,11 @@
 import kotlin.Lazy;
 import kotlin.LazyKt;
 
+/**
+ * A packet reader that runs on a TAP interface.
+ *
+ * It also implements facilities to reply to received packets.
+ */
 public class TapPacketReader extends PacketReader {
     private final FileDescriptor mTapFd;
     private final ArrayTrackRecord<byte[]> mReceivedPackets = new ArrayTrackRecord<>();
@@ -82,6 +87,14 @@
         return mReceivedPackets;
     }
 
+    /*
+     * Send a response on the TAP interface.
+     *
+     * The passed ByteBuffer is flipped after use.
+     *
+     * @param packet The packet to send.
+     * @throws IOException if the interface can't be written to.
+     */
     public void sendResponse(final ByteBuffer packet) throws IOException {
         try (FileOutputStream out = new FileOutputStream(mTapFd)) {
             byte[] packetBytes = new byte[packet.limit()];
diff --git a/staticlibs/hostdevice/com/android/testutils/ExceptionUtils.java b/staticlibs/hostdevice/com/android/testutils/ExceptionUtils.java
index e7dbed5..d3bda98 100644
--- a/staticlibs/hostdevice/com/android/testutils/ExceptionUtils.java
+++ b/staticlibs/hostdevice/com/android/testutils/ExceptionUtils.java
@@ -18,6 +18,9 @@
 
 import java.util.function.Supplier;
 
+/**
+ * A class grouping some utilities to deal with exceptions.
+ */
 public class ExceptionUtils {
     /**
      * Like a Consumer, but declared to throw an exception.
@@ -25,6 +28,7 @@
      */
     @FunctionalInterface
     public interface ThrowingConsumer<T> {
+        /** @see java.util.function.Consumer */
         void accept(T t) throws Exception;
     }
 
@@ -34,6 +38,7 @@
      */
     @FunctionalInterface
     public interface ThrowingSupplier<T> {
+        /** @see java.util.function.Supplier */
         T get() throws Exception;
     }
 
@@ -42,10 +47,15 @@
      */
     @FunctionalInterface
     public interface ThrowingRunnable {
+        /** @see java.lang.Runnable */
         void run() throws Exception;
     }
 
-
+    /**
+     * Convert a supplier that throws into one that doesn't.
+     *
+     * The returned supplier returns null in cases where the source throws.
+     */
     public static <T> Supplier<T> ignoreExceptions(ThrowingSupplier<T> func) {
         return () -> {
             try {
@@ -56,6 +66,11 @@
         };
     }
 
+    /**
+     * Convert a runnable that throws into one that doesn't.
+     *
+     * All exceptions are ignored by the returned Runnable.
+     */
     public static Runnable ignoreExceptions(ThrowingRunnable r) {
         return () -> {
             try {
diff --git a/staticlibs/hostdevice/com/android/testutils/MiscAsserts.kt b/staticlibs/hostdevice/com/android/testutils/MiscAsserts.kt
index 32c22c2..4e86360 100644
--- a/staticlibs/hostdevice/com/android/testutils/MiscAsserts.kt
+++ b/staticlibs/hostdevice/com/android/testutils/MiscAsserts.kt
@@ -34,7 +34,7 @@
     assertEquals(expected, len, "Expected array of length $expected, but was $len for $got")
 }
 
-// Bridge method to help write this in Java. If you're writing Kotlin, consider using native
+// Bridge method to help write this in Java. If you're writing Kotlin, consider using
 // kotlin.test.assertFailsWith instead, as that method is reified and inlined.
 fun <T : Exception> assertThrows(expected: Class<T>, block: ThrowingRunnable): T {
     return assertFailsWith(expected.kotlin) { block.run() }