From df35387dad20560690740061ba77d040af92225a Mon Sep 17 00:00:00 2001
From: Elliotte Rusty Harold <elharo@google.com>
Date: Wed, 13 Jan 2021 11:52:33 -0500
Subject: [PATCH 1/2] replace non-precondition use of Preconditions

---
 .../google/auth/oauth2/OAuth2Credentials.java | 27 ++++++++++++-------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/oauth2_http/java/com/google/auth/oauth2/OAuth2Credentials.java b/oauth2_http/java/com/google/auth/oauth2/OAuth2Credentials.java
index ab6c042da..f7bef6502 100644
--- a/oauth2_http/java/com/google/auth/oauth2/OAuth2Credentials.java
+++ b/oauth2_http/java/com/google/auth/oauth2/OAuth2Credentials.java
@@ -37,7 +37,6 @@
 import com.google.auth.http.AuthHttpConstants;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.MoreObjects;
-import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
 import java.io.IOException;
@@ -131,7 +130,10 @@ public void getRequestMetadata(
         super.getRequestMetadata(uri, executor, callback);
         return;
       }
-      metadata = Preconditions.checkNotNull(requestMetadata, "cached requestMetadata");
+      if (requestMetadata == null) {
+        throw new NullPointerException("cached requestMetadata");
+      }
+      metadata = requestMetadata;
     }
     callback.onSuccess(metadata);
   }
@@ -146,7 +148,10 @@ public Map<String, List<String>> getRequestMetadata(URI uri) throws IOException
       if (shouldRefresh()) {
         refresh();
       }
-      return Preconditions.checkNotNull(requestMetadata, "requestMetadata");
+      if (requestMetadata == null) {
+        throw new NullPointerException("requestMetadata");
+      }
+      return requestMetadata;
     }
   }
 
@@ -156,9 +161,11 @@ public void refresh() throws IOException {
     synchronized (lock) {
       requestMetadata = null;
       temporaryAccess = null;
-      useAccessToken(
-          Preconditions.checkNotNull(refreshAccessToken(), "new access token"),
-          getAdditionalHeaders());
+      AccessToken accessToken = refreshAccessToken();
+      if (accessToken == null) {
+        throw new NullPointerException("new access token");
+      }
+      useAccessToken(accessToken, getAdditionalHeaders());
       if (changeListeners != null) {
         for (CredentialsChangedListener listener : changeListeners) {
           listener.onChanged(this);
@@ -214,8 +221,10 @@ private boolean shouldRefresh() {
    * <p>Throws IllegalStateException if not overridden since direct use of OAuth2Credentials is only
    * for temporary or non-refreshing access tokens.
    *
-   * @return Refreshed access token.
-   * @throws IOException from derived implementations
+   * @return never
+   * @throws IllegalStateException always. OAuth2Credentials does not support refreshing the
+   *    access token. An instance with a new access token or a derived type
+        that supports refreshing should be used instead.
    */
   public AccessToken refreshAccessToken() throws IOException {
     throw new IllegalStateException(
@@ -230,7 +239,7 @@ public AccessToken refreshAccessToken() throws IOException {
    * <p>This is called when token content changes, such as when the access token is refreshed. This
    * is typically used by code caching the access token.
    *
-   * @param listener The listener to be added.
+   * @param listener the listener to be added
    */
   public final void addChangeListener(CredentialsChangedListener listener) {
     synchronized (lock) {

From cd9274e99e87fde85641c69a2b1c113c9e70a813 Mon Sep 17 00:00:00 2001
From: Elliotte Rusty Harold <elharo@google.com>
Date: Wed, 13 Jan 2021 12:55:19 -0500
Subject: [PATCH 2/2] format

---
 .../java/com/google/auth/oauth2/OAuth2Credentials.java      | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/oauth2_http/java/com/google/auth/oauth2/OAuth2Credentials.java b/oauth2_http/java/com/google/auth/oauth2/OAuth2Credentials.java
index f7bef6502..f22d3c74e 100644
--- a/oauth2_http/java/com/google/auth/oauth2/OAuth2Credentials.java
+++ b/oauth2_http/java/com/google/auth/oauth2/OAuth2Credentials.java
@@ -222,9 +222,9 @@ private boolean shouldRefresh() {
    * for temporary or non-refreshing access tokens.
    *
    * @return never
-   * @throws IllegalStateException always. OAuth2Credentials does not support refreshing the
-   *    access token. An instance with a new access token or a derived type
-        that supports refreshing should be used instead.
+   * @throws IllegalStateException always. OAuth2Credentials does not support refreshing the access
+   *     token. An instance with a new access token or a derived type that supports refreshing
+   *     should be used instead.
    */
   public AccessToken refreshAccessToken() throws IOException {
     throw new IllegalStateException(