How to add openvidu-java-client in gradle project

Question

I am tring to add openvidu-java-client to an existing multi-module gradle project but I get the following error :

Errors occurred while build effective model from /Users/xxxx/.gradle/caches/modules-2/files-2.1/io.openvidu/openvidu-java-client/2.20.0/d1b4db33036a286e7eeec5ece212c07e74417e60/openvidu-java-client-2.20.0.pom:
'dependencies.dependency.version' for com.google.code.gson:gson:jar must be a valid version but is '${version.gson}'. in io.openvidu:openvidu-java-client:2.20.0
'dependencies.dependency.version' for org.slf4j:slf4j-api:jar must be a valid version but is '${version.slf4j}'. in io.openvidu:openvidu-java-client:2.20.0
Errors occurred while build effective model from /Users/xxxx/.gradle/caches/modules-2/files-2.1/io.openvidu/openvidu-java-client/2.20.0/d1b4db33036a286e7eeec5ece212c07e74417e60/openvidu-java-client-2.20.0.pom:
'dependencies.dependency.version' for com.google.code.gson:gson:jar must be a valid version but is '${version.gson}'. in io.openvidu:openvidu-java-client:2.20.0
'dependencies.dependency.version' for org.slf4j:slf4j-api:jar must be a valid version but is '${version.slf4j}'. in io.openvidu:openvidu-java-client:2.20.0

I am kind of new with gradle here is my build.gradle file :

repositories {
    mavenCentral()
}

dependencies {
    implementation 'io.openvidu:openvidu-java-client:2.20.0'
}

bootJar {
    enabled = false
}

jar {
    enabled = true
}