After upgrading infobip-api-php-client to 6.2.1, creating a registered WhatsApp template via createWhatsAppTemplateRequest failed with BADREQUEST ("Invalid request body."). The serialized request body was missing the category field entirely: {"name":"ddintro_2","language":"en","allowCategoryChange":false,"structure":{...}}. The DiscriminatorMap on WhatsAppTemplatePublicApiRequest used category to pick the concrete subclass, and instantiating the base WhatsAppTemplatePublicApiRequest directly meant the category never got serialized.