Proxy configuration fails if user/password are not configured

As described in the TeamCity Artifactory Plugin documentation, in order to configure a proxy for Artifactory, the following 4 properties should be configured in TeamCity's $TEAMCITY_USER_HOME/.BuildServer/config/internal.properties file:

org.jfrog.artifactory.proxy.host
org.jfrog.artifactory.proxy.port
org.jfrog.artifactory.proxy.username
org.jfrog.artifactory.proxy.password

In case the above username and password properties are not added (because the proxy does not require authentication), the plugin will fail with the following error:

jetbrains/buildServer/serverSide/impl/BuildRunnerDescriptorImpl.addRunnerParameter must not be null

The workaround for this issue is to add the 2 properties with dummy values.
We would like to have this issue fixed and have the 2 properties optional.