Magento – How to convert this object data into array

I have this Data Object value.

Magento\Customer\Model\Data\AttributeMetadata Object
(
    [_data:protected] => Array
        (
            [frontend_input] => boolean
            [input_filter] => 
            [store_label] => Verified Buyer
            [validation_rules] => Array
                (
                )

            [multiline_count] => 0
            [visible] => 1
            [required] => 
            [data_model] => 
            [options] => Array
                (
                )

            [frontend_class] => 
            [user_defined] => 1
            [sort_order] => 90
            [frontend_label] => Verified Buyer
            [note] => 
            [system] => 
            [backend_type] => int
            [is_used_in_grid] => 
            [is_visible_in_grid] => 
            [is_filterable_in_grid] => 
            [is_searchable_in_grid] => 
            [attribute_code] => verified_buyer
        )

)

I converted this to

$array = (array) $customAttr;

But still I am reciving the object

Array
(
    [*_data] => Array
        (
            [frontend_input] => boolean
            [input_filter] => 
            [store_label] => Verified Buyer
            [validation_rules] => Array
                (
                )

            [multiline_count] => 0
            [visible] => 1
            [required] => 
            [data_model] => 
            [options] => Array
                (
                )

            [frontend_class] => 
            [user_defined] => 1
            [sort_order] => 90
            [frontend_label] => Verified Buyer
            [note] => 
            [system] => 
            [backend_type] => int
            [is_used_in_grid] => 
            [is_visible_in_grid] => 
            [is_filterable_in_grid] => 
            [is_searchable_in_grid] => 
            [attribute_code] => verified_buyer
        )

)

I am expecting output like

Array
(
            [frontend_input] => boolean
            [input_filter] => 
            [store_label] => Verified Buyer
            [validation_rules] => Array
                (
                )

            [multiline_count] => 0
            [visible] => 1
            [required] => 
            [data_model] => 
            [options] => Array
                (
                )

            [frontend_class] => 
            [user_defined] => 1
            [sort_order] => 90
            [frontend_label] => Verified Buyer
            [note] => 
            [system] => 
            [backend_type] => int
            [is_used_in_grid] => 
            [is_visible_in_grid] => 
            [is_filterable_in_grid] => 
            [is_searchable_in_grid] => 
            [attribute_code] => verified_buyer
)

Above all is Magento Customer custom attributes data.

Note : I am using REST API