Custom Repository for Library Gradle in android

Question

I am creating Android library module in which I need to include a dependency which require authentication and hence its username and password I can't share with my sdk users.When I am setting custom url in my library build.gradle it is not looking for repository. When I put custom repository url in project level gradle it works but it is not working. Code sample:

Library Gradle:

apply plugin: 'com.android.library'

repositories {
    maven {
        url "https://custom.bintray.com"
    }
    maven {
        url "http://custom.bintray.com"
        credentials {
            username 'asfsafasf'
            password 'asdasfsf'
        }
    }
}
dependencies{
    implementation <gradle path of library present in above custom repo>
}

When I am using my library gradle in my project it is not able to resolve repository