fix: update StorageOptions to not overwrite any previously set host (#…

…1142)

When calling `StorageOptions#toBuilder()` after creating the builder the host was explicitly set to the default host. This change removes that behavior instead moving the setting of the default host to the instantiation of a new builder.

Add unit tests to ensure host is set to the expected values based on different ways of creating an instance of StorageOptions.

Related:
* googleapis/google-cloud-java#6579
* googleapis/google-cloud-java#7004
* googleapis/google-cloud-java#7034

google-cloud-storage/src/main/java/com/google/cloud/storage/StorageOptions.java

@@ -166,7 +166,7 @@ public static StorageOptions getUnauthenticatedInstance() {
   @SuppressWarnings("unchecked")
   @Override
   public Builder toBuilder() {
-    return new Builder(this).setHost(DEFAULT_HOST);
+    return new Builder(this);
   }
 
   @Override

google-cloud-storage/src/test/java/com/google/cloud/storage/StorageOptionsTest.java

@@ -16,6 +16,8 @@
 
 package com.google.cloud.storage;
 
+import static com.google.common.truth.Truth.assertThat;
+
 import com.google.cloud.TransportOptions;
 import org.easymock.EasyMock;
 import org.junit.Assert;
@@ -33,4 +35,34 @@ public void testInvalidTransport() {
       Assert.assertNotNull(ex.getMessage());
     }
   }
+
+  @Test
+  public void testConfigureHostShouldBeKeptOnToBuilder() {
+    StorageOptions opts1 = StorageOptions.newBuilder().setHost("custom-host").build();
+    StorageOptions opts2 = opts1.toBuilder().build();
+
+    assertThat(opts2.getHost()).isEqualTo("custom-host");
+  }
+
+  @Test
+  public void testToBuilderShouldSpecifyDefaultIfNotOtherwiseSet() {
+    StorageOptions opts1 = StorageOptions.newBuilder().build();
+    StorageOptions opts2 = opts1.toBuilder().build();
+
+    assertThat(opts2.getHost()).isEqualTo("https://storage.googleapis.com");
+  }
+
+  @Test
+  public void testNewBuilderSpecifiesCorrectHost() {
+    StorageOptions opts1 = StorageOptions.newBuilder().build();
+
+    assertThat(opts1.getHost()).isEqualTo("https://storage.googleapis.com");
+  }
+
+  @Test
+  public void testDefaultInstanceSpecifiesCorrectHost() {
+    StorageOptions opts1 = StorageOptions.getDefaultInstance();
+
+    assertThat(opts1.getHost()).isEqualTo("https://storage.googleapis.com");
+  }
 }