Bug 129377 [Viewers] IDecorationContext.getContextIds() comment says it should be removed before M5
There is a similar comment in DecorationContext.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/DecorationContext.java
}
	/* (non-Javadoc)
	 * @see org.eclipse.jface.viewers.IDecorationContext#getProperty(java.lang.String)
	 */
	public Object getProperty(String property) {
		return properties.get(property);
	}
	/* (non-Javadoc)
	 * @see org.eclipse.jface.viewers.IDecorationContext#getProperties()
	 */
	public String[] getProperties() {
		return (String[]) properties.keySet().toArray(new String[properties.size()]);
	}
	/**
	 * Set the pgiven roperty to the given value. Setting the value of
	 * a propert to <code>null</code> removes the property from
	 * the context.
	 * @param property the property
	 * @param value the value of the property or <code>null</code>
	 * if the property is to be removed.
	 */
	public void putProperty(String property, Object value) {
		if (value == null) {
			properties.remove(property);
		} else {
			properties.put(property, value);
		}
	}
}