Just did the same thing locally (outside of the docker build) and had the same problem:
E:\Code\hapi-fhir-jpaserver-starter (rel_5_3_0 -> origin)
λ mvn -ntp dependency:go-offline
[INFO] Scanning for projects...
[WARNING] The project ca.uhn.hapi.fhir:hapi-fhir-jpaserver-starter:war:5.3.0-SNAPSHOT uses prerequisites which is only intended for maven-plugin projects but not for non maven-plugin projects. For such purposes you should use the maven-enforcer-plugin. See
https://maven.apache.org/enforcer/enforcer-rules/requireMavenVersion.html[INFO]
[INFO] ------------< ca.uhn.hapi.fhir:hapi-fhir-jpaserver-starter >------------
[INFO] Building HAPI FHIR JPA Server - Starter Project 5.3.0-SNAPSHOT
[INFO] --------------------------------[ war ]---------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:3.1.2:go-offline (default-cli) @ hapi-fhir-jpaserver-starter ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 5.686 s
[INFO] Finished at: 2021-02-04T10:20:15-08:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-dependency-plugin:3.1.2:go-offline (default-cli) on project hapi-fhir-jpaserver-starter: org.eclipse.aether.resolution.DependencyResolutionException: Could not find artifact ca.uhn.hapi.fhir:hapi-fhir-testpage-overlay:jar:5.3.0-SNAPSHOT in oss-snapshots (
https://oss.sonatype.org/content/repositories/snapshots/) -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1]
http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException