Returns a Hash of attributes with an array of
their error details.
Updating this hash would still update errors state for backward
compatibility, but this behavior is deprecated.
# File activemodel/lib/active_model/errors.rb, line 348
def details
hash = group_by_attribute.transform_values do |errors|
errors.map(&:details)
end
DeprecationHandlingDetailsHash.new(hash)
end