Add hooks to alter the behavior during the request translation to the translators

1. +++ b/src/Entity/Job.php
   @@ -364,9 +374,18 @@ class Job extends ContentEntityBase implements EntityOwnerInterface, JobInterfac
   +      $all_items = \Drupal::entityTypeManager()->getStorage('tmgmt_job_item')->loadMultiple($results);
   +      $items = $all_items;
   +      if ($this->requestingTranslation) {
   +        /** @var \Drupal\tmgmt\JobItemInterface $item */
   +        foreach ($all_items as $key => $item) {
   +          if ($item->getCountPending() == 0) {
   +            unset($items[$key]);
   

   No need for $all_items? You could also use array_filter to simplify this:

   $items = array_filter($items, function (JobInterface $item) { $item->getCountPending() > 0; }));

2. +++ b/src/Entity/Job.php
   @@ -689,10 +708,19 @@ class Job extends ContentEntityBase implements EntityOwnerInterface, JobInterfac
   +
   +    \Drupal::moduleHandler()->invokeAll('tmgmt_job_before_request_translation', [$this->getItems()]);
   +
   +    $this->requestingTranslation = TRUE;
   ...
   +
   +    $this->requestingTranslation = FALSE;
   +
   +    \Drupal::moduleHandler()->invokeAll('tmgmt_job_after_request_translation', [$this->getItems()]);
   

   Needs comments to explain those lines.

3. +++ b/tmgmt.module
   @@ -102,9 +102,19 @@ function tmgmt_cron() {
   -    foreach ($job_items_by_job as $items) {
   +    foreach ($job_items_by_job as $all_items) {
   +      $items = $all_items;
          $translator = reset($items)->getTranslatorPlugin();
   -      $translator->requestJobItemsTranslation($items);
   +      \Drupal::moduleHandler()->invokeAll('tmgmt_job_before_request_translation', [$all_items]);
   +      foreach ($all_items as $key => $item) {
   +        if ($item->getCountPending() == 0) {
   +          unset($items[$key]);
   +        }
   +      }
   

   Same here

Not a big fan of the requestingTranslation flag but I don't really have any better ideas. I think we need to find a better name however, instead of naming it after the context, lets name it after what we use it for. $this->filterTranslatedItems maybe? Should require less comments to explain what it is for.

We should also add @see documentation to the two hooks we're calling on requestTranslation and possibly also mention this concept on the translator requestTranslation() method docs, something along the lines of "During the translation process, Job::getItems() will only return job items that are not already fully translated.".

diff --git a/src/Entity/Job.php b/src/Entity/Job.php
index 57e444c..b46a8c5 100644
--- a/src/Entity/Job.php
+++ b/src/Entity/Job.php
@@ -700,7 +700,6 @@ class Job extends ContentEntityBase implements EntityOwnerInterface, JobInterfac
     }
 
     // Call the hook before requesting the translation.
-    // @see hook_tmgmt_job_before_request_translation()
     \Drupal::moduleHandler()->invokeAll('tmgmt_job_before_request_translation', [$this->getItems()]);
 
     // We do not want to translate the items that are already translated.
@@ -712,7 +711,6 @@ class Job extends ContentEntityBase implements EntityOwnerInterface, JobInterfac
     $this->getTranslatorPlugin()->requestTranslation($this);
 
     // Reset it again so getData returns again all the values.
-    // @see hook_tmgmt_job_after_request_translation()
     $this->filterTranslatedItems = FALSE;
 
     // Call the hook after requesting the translation.
diff --git a/src/TranslatorPluginInterface.php b/src/TranslatorPluginInterface.php
index 300e569..053d80a 100644
--- a/src/TranslatorPluginInterface.php
+++ b/src/TranslatorPluginInterface.php
@@ -118,6 +118,9 @@ interface TranslatorPluginInterface extends PluginInspectionInterface {
    * @param \Drupal\tmgmt\JobInterface $job
    *   The job that should be submitted.
    *
+   * @see hook_tmgmt_job_before_request_translation()
+   * @see hook_tmgmt_job_after_request_translation()
+   *
    * @ingroup tmgmt_remote_languages_mapping
    */
   public function requestTranslation(JobInterface $job);

That's what I meant.

Edit: Forgot to mention, .. committed :)