public void setSeverity(final Severity severity) {
        final String newClassName = severity != null
                ? severityNameToClassMap.get(severity.name())
                : null;
        final String classAttr = getElement().getClassName();
        for (final String severityClassName : severityNameToClassMap.values()) {
            if (!severityClassName.equals(newClassName) && classAttr.contains(severityClassName)) {
//                GWT.log("Un-setting " + this.pipelineElement.getId() + " from " + severity);
                getElement().removeClassName(severityClassName);
            }
        }
        if (newClassName != null && !classAttr.contains(newClassName)) {
//            GWT.log("Setting " + this.pipelineElement.getId() + " to " + severity);
            getElement().addClassName(newClassName);
        }
        setSeverityHoverTip(severity);
    }
Set the severity for this pipe element or null if there isn't one.
Not all severities are rendered.
stroom-core-client/src/main/java/stroom/pipeline/structure/client/view/PipelineElementBox.java