The URL "/ " with trailing space is not getting recognized as <front>

Thank you for the fix! For getting this committed we need some additional tests though.
For the additional tests, I think extending \Drupal\Tests\link\Functional\LinkFieldTest would be the right place.

Setting to needs work based on #3

Extended \Drupal\Tests\link\Functional\LinkFieldTest as mentioned in #2. Hope for a green.
Please review.

It looks as though you imported a test class but we need a test.

@cilefen,

Any pointers on implementing that. Could use some advice.

#3 has some advice. You can modify that test class to cover that line.

@cilefen Can you please let me know what tests are required to write in this \Drupal\Tests\link\Functional\LinkFieldTest to validate, Should i create another function to validate or include this in this testURLValidation by adding more key/value pairs to this array valid_internal_entries ?

1. +++ b/core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php
   @@ -7,6 +7,7 @@
   +use Drupal\Tests\link\Functional\LinkFieldTest;
   

   We need to include new tests in that file to validate the proposed solution to the problem, not to include the file.

2. +++ b/core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php
   @@ -100,6 +101,7 @@ protected static function getUriAsDisplayableString($uri) {
   +    $string = trim($string);
   

   We need not an extra statement, we can add trim function directly as--
   $uri = trim($string);

The patch in #15 looks good to me.

Committed and pushed b98cdcad61 to 8.6.x and 4c944ba64e to 8.5.x. Thanks!

Backported to 8.5.x because this is a bugfix with no BC implications.

Nice usability improvement 👌 Thanks!