Symfony NotBlank constraint allow blank string
I think this is because you've declared your post operations attributes using camel case instead of snake case. Camel case must be used at the top-level of the ApiResource annotation only.
Currently, you've only declared the method of your operation. This is useless here.
- normalizationContext => normalization_context
- validationGroups => validation_groups
Also you've declared a mehtod property instead of method within you GET operation.