code: public void setNamespaceProperty(String key, Object value, String namespace)
      {
          try {
              this.propertiesLock.lock();
  
              Map<String, Object> namespaceProperties = getNamespaceProperties(namespace);
              if (namespaceProperties != null) {
                  namespaceProperties.put(key, value);
              }
          } finally {
              this.propertiesLock.unlock();
          }
      }
docs: Sets the value of the specified extension property on the given namespace.
  
  @param key the extension property to set
  @param value the property value
  @param namespace the namespace to associate the property with, {@code null} for the root namespace
  @since 7.0M2