OpenApiGenerator Warnings

I am using OpenApiGenerator, and I am generating some types in my pom.xml file using some type mappings, here is an example

                <typeMappings>
                    <typeMapping>PdfFileFormat=Flux&lt;DataBuffer&gt; </typeMapping>
                </typeMappings>

or like this one :

                <typeMappings>
                    <typeMapping>SetOfItels=Set&lt;MyItems&gt;</typeMapping>
                </typeMappings>

And When I am generating, I am getting the following warnings :

[[1;33mWARNING[m] Unknown type found in the schema: PdfFileFormat

So my question is: How can I get rid of these warnings? and I do have a bunch of them

openapi-generator version

I am using version 5.4.0

And Thank you