public Builder clearLoginUrl() {
          loginUrl_ = getDefaultInstance().getLoginUrl();
          bitField0_ = (bitField0_ & ~0x00000004);
          onChanged();
          return this;
        }
<pre>
Required. The login form URL of the website.
</pre>

<code>string login_url = 3 [(.google.api.field_behavior) = REQUIRED];</code>

@return This builder for chaining.
java-websecurityscanner/proto-google-cloud-websecurityscanner-v1alpha/src/main/java/com/google/cloud/websecurityscanner/v1alpha/ScanConfig.java