Generate an Apex from WSDL

[lds8437]

I generated the Metadata WSDL page and saved the WSDL file on my computer. Then I tried to generate an Apex from WSDL file in Salesforce. I was able to see the prase successful message.
Parse successful: Warnings 0, Errors 0
but when I was clicking on Generate Apex code getting the below error.
Apex Generation Failed
Unable to find complexType for (URL) FlexipageDataSource

Here is the code that I am getting an error:

<xsd:complexType name="QuickActionListItem">
    <xsd:sequence>
     <xsd:element name="quickActionName" type="xsd:string"/>
    </xsd:sequence>
   </xsd:complexType>
   <xsd:complexType name="FlexiPageTemplateInstance">
    <xsd:sequence>
     <xsd:element name="flexipageDataSources" minOccurs="0" maxOccurs="unbounded" type="tns:FlexipageDataSource"/>
     <xsd:element name="identifier" minOccurs="0" type="xsd:string"/>
     <xsd:element name="name" type="xsd:string"/>
     <xsd:element name="properties" minOccurs="0" maxOccurs="unbounded" type="tns:ComponentInstanceProperty"/>
     <xsd:element name="schemaProperties" minOccurs="0" maxOccurs="unbounded" type="tns:FlexiPageCompSchemaPropertyDef"/>
    </xsd:sequence>
   </xsd:complexType>

I would appreciate it if anyone could answer and give me a direction.