Can publish to mavenLocal but not remote repo?

Question

$ ./gradlew -version

------------------------------------------------------------
Gradle 6.5
------------------------------------------------------------

Build time:   2020-06-02 20:46:21 UTC
Revision:     a27f41e4ae5e8a41ab9b19f8dd6d86d7b384dad4

Kotlin:       1.3.72
Groovy:       2.5.11
Ant:          Apache Ant(TM) version 1.10.7 compiled on September 1 2019
JVM:          1.8.0_181 (Oracle Corporation 25.181-b13)
OS:           Mac OS X 10.15.7 x86_64

I have a sub-project with the following build.gradle file

plugins {
    id 'java'
    id 'maven-publish'
}

dependencies {
    compileOnly group: 'org.projectlombok', name: 'lombok', version: '1.18.10'
    annotationProcessor group: 'org.projectlombok', name: 'lombok', version: '1.18.10'

    compile group: 'javax.validation', name: 'validation-api', version: '2.0.1.Final'
}

task sourcesJar(type: Jar, dependsOn: classes){
    from sourceSets.main.allSource
}

artifacts{
    archives sourcesJar
}

publishing {
    repositories{
        maven {
            url 's3://' + s3_bucket
            authentication {
                awsIm(AwsImAuthentication)
            }
        }
    }
    publications {
        integrationsCommon(MavenPublication){
            artifactId artifactId
            from components.java
            artifact sourcesJar{
                classifier "sources"
            }
        }
    }
}

I can run

$ ./gradlew clean build pTML -p my-sub-project

...and see the artifact published in my ~/.m2 local repo.

But I get the following error when I run the publish task

$ ./gradlew clean build publish -p my-sub-project
* What went wrong:
Execution failed for task ':my-sub-project:publishIntegrationsCommonPublicationToMaven2Repository'.
> Failed to publish publication 'integrationsCommon' to repository 'maven2'
   > java.lang.NullPointerException (no error message)

Why is that? I was under the impression that if can publish to Maven local I can publish anywhere! (God I miss Maven!).

Answer 1

The AWS documentation suggest to define credentials.

This just refers to CodeArtifact instead of S3, which appears to be the common back-end. If you want to use S3 instead... add --stacktrace to the command, in order to determine what that NullPointerException may be caused by; the configuration may lack something essential.

This would be the Gradle documentation for S3: AWS S3 repositories configuration .