chore: Refactor parseJsonInputStream to only accept credentialStream

Author: lqiu96

oauth2_http/java/com/google/auth/oauth2/ExternalAccountAuthorizedUserCredentials.java

@@ -160,7 +160,8 @@ public static ExternalAccountAuthorizedUserCredentials fromStream(InputStream cr
    */
   public static ExternalAccountAuthorizedUserCredentials fromStream(
       InputStream credentialsStream, HttpTransportFactory transportFactory) throws IOException {
-    GenericJson fileContents = parseJsonInputStream(credentialsStream, transportFactory);
+    Preconditions.checkNotNull(transportFactory);
+    GenericJson fileContents = parseJsonInputStream(credentialsStream);
     String fileType = (String) fileContents.get("type");
     if (fileType == null) {
       throw new IOException("Error reading credentials from stream, 'type' field not specified.");

oauth2_http/java/com/google/auth/oauth2/ExternalAccountCredentials.java

@@ -39,6 +39,7 @@
 import com.google.auth.RequestMetadataCallback;
 import com.google.auth.http.HttpTransportFactory;
 import com.google.common.base.MoreObjects;
+import com.google.common.base.Preconditions;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.IOException;
 import java.io.InputStream;
@@ -385,7 +386,8 @@ public static ExternalAccountCredentials fromStream(InputStream credentialsStrea
    */
   public static ExternalAccountCredentials fromStream(
       InputStream credentialsStream, HttpTransportFactory transportFactory) throws IOException {
-    GenericJson fileContents = parseJsonInputStream(credentialsStream, transportFactory);
+    Preconditions.checkNotNull(transportFactory);
+    GenericJson fileContents = parseJsonInputStream(credentialsStream);
     String fileType = (String) fileContents.get("type");
     if (fileType == null) {
       throw new IOException("Error reading credentials from stream, 'type' field not specified.");

oauth2_http/java/com/google/auth/oauth2/GdchCredentials.java

@@ -101,7 +101,7 @@ public class GdchCredentials extends GoogleCredentials {
   }
 
   /**
-   * Returns credentials defined by a GDCHCredential key file in JSON format from the Google
+   * Returns credentials defined by a GdchCredentials key file in JSON format from the Google
    * Developers Console.
    *
    * <p>Important: If you accept a credential configuration (credential JSON/File/Stream) from an
@@ -120,7 +120,7 @@ public static GdchCredentials fromStream(InputStream credentialsStream) throws I
   }
 
   /**
-   * Returns credentials defined by a GDCHCredential key file in JSON format from the Google
+   * Returns credentials defined by a GdchCredentials key file in JSON format from the Google
    * Developers Console.
    *
    * <p>Important: If you accept a credential configuration (credential JSON/File/Stream) from an
@@ -138,7 +138,8 @@ public static GdchCredentials fromStream(InputStream credentialsStream) throws I
    */
   public static GdchCredentials fromStream(
       InputStream credentialsStream, HttpTransportFactory transportFactory) throws IOException {
-    GenericJson fileContents = parseJsonInputStream(credentialsStream, transportFactory);
+    Preconditions.checkNotNull(transportFactory);
+    GenericJson fileContents = parseJsonInputStream(credentialsStream);
     String fileType = (String) fileContents.get("type");
     if (fileType == null) {
       throw new IOException("Error reading credentials from stream, 'type' field not specified.");

oauth2_http/java/com/google/auth/oauth2/GoogleCredentials.java

@@ -32,7 +32,6 @@
 package com.google.auth.oauth2;
 
 import com.google.api.client.json.GenericJson;
-import com.google.api.client.json.JsonFactory;
 import com.google.api.client.json.JsonObjectParser;
 import com.google.api.client.util.Preconditions;
 import com.google.api.core.ObsoleteApi;
@@ -235,13 +234,13 @@ public static GoogleCredentials fromStream(InputStream credentialsStream) throws
     return fromStream(credentialsStream, OAuth2Utils.HTTP_TRANSPORT_FACTORY);
   }
 
-  static GenericJson parseJsonInputStream(
-      InputStream credentialsStream, HttpTransportFactory transportFactory) throws IOException {
+  /**
+   * Parses the Credential InputStream into JSON for each credential subclass to consume. The
+   * Credential InputStream must be non-null and valid.
+   */
+  static GenericJson parseJsonInputStream(InputStream credentialsStream) throws IOException {
     Preconditions.checkNotNull(credentialsStream);
-    Preconditions.checkNotNull(transportFactory);
-
-    JsonFactory jsonFactory = OAuth2Utils.JSON_FACTORY;
-    JsonObjectParser parser = new JsonObjectParser(jsonFactory);
+    JsonObjectParser parser = new JsonObjectParser(OAuth2Utils.JSON_FACTORY);
     return parser.parseAndClose(credentialsStream, StandardCharsets.UTF_8, GenericJson.class);
   }
 
@@ -286,7 +285,8 @@ static GenericJson parseJsonInputStream(
       "This method is obsolete because of a potential security risk. Use the credential specific load method instead")
   public static GoogleCredentials fromStream(
       InputStream credentialsStream, HttpTransportFactory transportFactory) throws IOException {
-    GenericJson fileContents = parseJsonInputStream(credentialsStream, transportFactory);
+    Preconditions.checkNotNull(transportFactory);
+    GenericJson fileContents = parseJsonInputStream(credentialsStream);
     String fileType = (String) fileContents.get("type");
     if (fileType == null) {
       throw new IOException("Error reading credentials from stream, 'type' field not specified.");

oauth2_http/java/com/google/auth/oauth2/ImpersonatedCredentials.java

@@ -401,7 +401,8 @@ public static ImpersonatedCredentials fromStream(InputStream credentialsStream)
    */
   public static ImpersonatedCredentials fromStream(
       InputStream credentialsStream, HttpTransportFactory transportFactory) throws IOException {
-    GenericJson fileContents = parseJsonInputStream(credentialsStream, transportFactory);
+    Preconditions.checkNotNull(transportFactory);
+    GenericJson fileContents = parseJsonInputStream(credentialsStream);
     String fileType = (String) fileContents.get("type");
     if (fileType == null) {
       throw new IOException("Error reading credentials from stream, 'type' field not specified.");

oauth2_http/java/com/google/auth/oauth2/ServiceAccountCredentials.java

@@ -486,7 +486,8 @@ public static ServiceAccountCredentials fromStream(InputStream credentialsStream
    */
   public static ServiceAccountCredentials fromStream(
       InputStream credentialsStream, HttpTransportFactory transportFactory) throws IOException {
-    GenericJson fileContents = parseJsonInputStream(credentialsStream, transportFactory);
+    Preconditions.checkNotNull(transportFactory);
+    GenericJson fileContents = parseJsonInputStream(credentialsStream);
     String fileType = (String) fileContents.get("type");
     if (fileType == null) {
       throw new IOException("Error reading credentials from stream, 'type' field not specified.");

oauth2_http/java/com/google/auth/oauth2/UserCredentials.java

@@ -172,7 +172,8 @@ public static UserCredentials fromStream(InputStream credentialsStream) throws I
    */
   public static UserCredentials fromStream(
       InputStream credentialsStream, HttpTransportFactory transportFactory) throws IOException {
-    GenericJson fileContents = parseJsonInputStream(credentialsStream, transportFactory);
+    Preconditions.checkNotNull(transportFactory);
+    GenericJson fileContents = parseJsonInputStream(credentialsStream);
     String fileType = (String) fileContents.get("type");
     if (fileType == null) {
       throw new IOException("Error reading credentials from stream, 'type' field not specified.");

oauth2_http/javatests/com/google/auth/oauth2/GoogleCredentialsTest.java

@@ -155,9 +155,7 @@ public void fromStream_noType_throws() throws IOException {
   @Test
   public void fromStream_nullStream_throws() {
     MockHttpTransportFactory transportFactory = new MockHttpTransportFactory();
-    assertThrows(
-        NullPointerException.class,
-        () -> GoogleCredentials.parseJsonInputStream(null, transportFactory));
+    assertThrows(NullPointerException.class, () -> GoogleCredentials.parseJsonInputStream(null));
   }
 
   @Test