Could not run build action using Gradle distribution: Could not get unknown property

If my build.gradle uses two external properties artifactory_user and artifactory_password, and I have them defined inside ~/.gradle/gradle.properties, VS Code does not look them up and fails:

buildscript {
    repositories {
        maven {
            url 'https://artifactory.example.com'
            credentials {
                username = "${artifactory_user}"
                password = "${artifactory_password}"
            }
        }
    }
}

Error message:

Could not run build action using Gradle distribution 'https://artifactory.example.com/gradle-cache/gradle-4.5-bin.zip'.
Build file '/Users/someuser/someproj/build.gradle' line: ...
A problem occurred evaluating root project 'someproj'.
Could not get unknown property 'artifactory_user' for Credentials [username: null] of type 

Environment

• Operating System: macOS 10.14.5
• JDK version: OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.212-b03, mixed mode)
• Visual Studio Code version: 1.35.0
• Java extension version: 0.46.0

Steps To Reproduce

1. Define a couple of properties in your ~/.gradle/gradle.properties
2. Use them in your build.gradle

Current Result

Could not run build action using Gradle distribution 'https://artifactory.example.com/gradle-cache/gradle-4.5-bin.zip'.
Build file '/Users/someuser/someproj/build.gradle' line: ...
A problem occurred evaluating root project 'someproj'.
Could not get unknown property 'artifactory_user' for Credentials [username: null] of type 

Expected Result

The artifactory_user and artifactory_password properties to be resolved.

Reproduce the failure using the issue's build.gradle and ~/.gradle/gradle.properties setup, then start with the Gradle build action that evaluates the build file. Trace how the external properties are loaded during that action. Done means the artifactory_user and artifactory_password properties resolve successfully and the build action completes.