Getting the description of "plural" entities does not work, this call:

introspectors.get("generic-vnfs").getMetadata(ObjectMetadata.DESCRIPTION)

returns NULL, but when we look at the OXM we see:

<xs:element name="generic-vnfs">
    <xs:complexType>
      <xs:annotation>
        <xs:appinfo>
          <annox:annotate target="class">@org.onap.aai.annotations.Metadata(description="Collection of VNFs")</annox:annotate>
        </xs:appinfo>
      </xs:annotation>
      <xs:sequence>
        <xs:element ref="tns:generic-vnf" minOccurs="0" maxOccurs="5000"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

As vk250x found out it is because:

"For only the plural objects such as generic-vnfs, tenants and etc, they have two xml-properties child nodes to the parent node java-type in the oxm files.

        <java-type name="GenericVnfs">

            <xml-properties>

                <xml-property name="description" value="Collection of VNFs"/>

            </xml-properties>

            <xml-root-element name="generic-vnfs"/>

            <java-attributes>

                <xml-element container-type="java.util.ArrayList" java-attribute="genericVnf" name="generic-vnf" type="inventory.aai.onap.org.v16.GenericVnf"/>

            </java-attributes>

            <xml-properties>

                <xml-property name="maximumDepth" value="0"/>

            </xml-properties>

        </java-type>

 __ 

It’s a bug in the oxm files it seems."