public String getCreationTimestamp() {
        return this.creationTimestamp;
    }
The time, in milliseconds since the epoch, when the core definition version was created.

@return The time, in milliseconds since the epoch, when the core definition version was created.
aws-java-sdk-greengrass/src/main/java/com/amazonaws/services/greengrass/model/GetCoreDefinitionVersionResult.java