generator/api/src/main/java/io/fabric8/maven/generator/api/support/BaseGenerator.java
private String getFromModeDefault(RuntimeMode mode) {
        if (mode == RuntimeMode.openshift && fromSelector != null && fromSelector.isRedHat()) {
            return "istag";
        } else {
            return "docker";
        }
    }
private String getFromModeDefault(RuntimeMode mode) {
        if (mode == RuntimeMode.openshift && fromSelector != null && fromSelector.isRedHat()) {
            return "istag";
        } else {
            return "docker";
        }
    }
Use "istag" as default for "redhat" versions of this plugin