Converts the Drupal field structure to a JSON:API array structure

The Issue Summary here is very difficult to understand. There is no proposed resolution to help guide the reviewer nor are there any tasks. I have added an Issue Summary update to the tasks to emphasize the need for it. See Write an issue summary for an existing issue → for guidance.

Adding tag for testing based on #9. I am setting this to needs work to complete the issue summary.

I believe this is a false positive.

$object->getCardinality() === 1
      ? array_shift($cacheable_normalizations) ?: CacheableNormalization::permanent(NULL)
      : CacheableNormalization::aggregate($cacheable_normalizations);

Is the same example 1 ? 2 ?: 3 : 4 from https://wiki.php.net/rfc/ternary_associativity which should not make any problems.

From the PHP documentation: Parentheses are also not required when nesting into the middle operand, as this is always unambiguous and not affected by associativity:

1 ? 2 ? 3 : 4 : 5 // ok
1 ? 2 ?: 3 : 4    // ok

This case is a PHP example and is correct according to documentation.