class SimpleForm::FormBuilder

def find_wrapper_mapping(input_type)

2) If not, it tries to find a config
1) It tries to find a wrapper for the current form

Attempts to find a wrapper mapping. It follows the following rules: 
def find_wrapper_mapping(input_type)
  if options[:wrapper_mappings] && options[:wrapper_mappings][input_type]
    options[:wrapper_mappings][input_type]
  else
    SimpleForm.wrapper_mappings && SimpleForm.wrapper_mappings[input_type]
  end
end