in src/main/java/org/apache/sling/discovery/commons/providers/DefaultInstanceDescription.java [193:201]
public void setProperty(String key, String value) {
if (!PropertyNameHelper.isValidPropertyName(key)) {
throw new IllegalArgumentException("key is not a valid property name: "+key);
}
if (properties == null) {
properties = new HashMap<String, String>();
}
properties.put(key, value);
}