Hi, While reviewing the module for best practices and standards. I have found this with the help of PHPCS:
phpcs --standard=Drupal,DrupalPractice --extensions=php,module,inc,install,test,profile,theme,css,info,txt,md,yml yaml_content/
FILE: /var/www/html/dContri/yaml_content/tests/src/Unit/Plugin/yaml_content/process/ReferenceTest.php
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FOUND 0 ERRORS AND 4 WARNINGS AFFECTING 4 LINES
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11 | WARNING | [x] Unused use statement
72 | WARNING | [ ] Line exceeds 80 characters; contains 84 characters
99 | WARNING | [ ] Line exceeds 80 characters; contains 84 characters
129 | WARNING | [ ] Line exceeds 80 characters; contains 84 characters
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PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/tests/src/Unit/EntityLoadHelper/EntityLoadHelperTest.php
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FOUND 3 ERRORS AND 8 WARNINGS AFFECTING 11 LINES
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32 | WARNING | [ ] Line exceeds 80 characters; contains 81 characters
149 | WARNING | [x] A comma should follow the last multiline array item. Found: '3c6485e4-69a3-429d-8ab1-3e7df48747bc'
179 | WARNING | [x] A comma should follow the last multiline array item. Found: '3c6485e4-69a3-429d-8ab1-3e7df48747bc'
259 | WARNING | [x] A comma should follow the last multiline array item. Found: '3c6485e4-69a3-429d-8ab1-3e7df48747bc'
274 | WARNING | [ ] Line exceeds 80 characters; contains 84 characters
289 | WARNING | [x] A comma should follow the last multiline array item. Found: '3c6485e4-69a3-429d-8ab1-3e7df48747bc'
305 | WARNING | [ ] Line exceeds 80 characters; contains 82 characters
334 | WARNING | [ ] Line exceeds 80 characters; contains 88 characters
574 | ERROR | [ ] Missing parameter type
589 | ERROR | [ ] Description for the @return value is missing
600 | ERROR | [ ] Description for the @return value is missing
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PHPCBF CAN FIX THE 4 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/tests/src/Unit/ContentLoader/ExistenceCheckingTest.php
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FOUND 1 ERROR AND 4 WARNINGS AFFECTING 5 LINES
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191 | ERROR | [x] Expected 1 blank line after function; 2 found
351 | WARNING | [ ] Unused variable $media_test.
352 | WARNING | [ ] Unused variable $file_test.
356 | WARNING | [ ] Unused variable $node_match_test.
358 | WARNING | [ ] Unused variable $node_no_match_test.
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PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/tests/src/Unit/ContentLoader/ContentLoaderTest.php
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FOUND 10 ERRORS AND 1 WARNING AFFECTING 11 LINES
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9 | WARNING | [x] Unused use statement
48 | ERROR | [x] Line indented incorrectly; expected 2 spaces, found 3
49 | ERROR | [x] Line indented incorrectly; expected 4 spaces, found 5
51 | ERROR | [x] Line indented incorrectly; expected 4 spaces, found 5
52 | ERROR | [x] Line indented incorrectly; expected 4 spaces, found 5
54 | ERROR | [x] Line indented incorrectly; expected 4 spaces, found 5
55 | ERROR | [x] Line indented incorrectly; expected 4 spaces, found 5
57 | ERROR | [x] Line indented incorrectly; expected 4 spaces, found 5
58 | ERROR | [x] Line indented incorrectly; expected 4 spaces, found 5
59 | ERROR | [x] Line indented incorrectly; expected 4 spaces, found 5
60 | ERROR | [x] Line indented incorrectly; expected 2 spaces, found 3
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PHPCBF CAN FIX THE 11 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/tests/src/Traits/LoadFixturesTrait.php
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FOUND 1 ERROR AFFECTING 1 LINE
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26 | ERROR | Missing parameter type
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FILE: /var/www/html/dContri/yaml_content/tests/src/Functional/Plugin/yaml_content/process/FileTest.php
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FOUND 1 ERROR AND 1 WARNING AFFECTING 2 LINES
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9 | WARNING | [x] Unused use statement
32 | ERROR | [ ] Missing member variable doc comment
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PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/tests/src/Functional/NodeImportTest.php
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FOUND 6 ERRORS AFFECTING 6 LINES
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26 | ERROR | [x] Do not append variable name "$contentDirectory" to the type declaration in a member variable comment
33 | ERROR | [x] Do not append variable name "$contentLoader" to the type declaration in a member variable comment
63 | ERROR | [x] Array indentation error, expected 6 spaces but found 8
64 | ERROR | [x] Array indentation error, expected 6 spaces but found 8
65 | ERROR | [x] Array closing indentation error, expected 4 spaces but found 6
108 | ERROR | [x] Missing function doc comment
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PHPCBF CAN FIX THE 6 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/tests/src/Functional/TaxonomyImportTest.php
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FOUND 2 ERRORS AND 1 WARNING AFFECTING 3 LINES
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23 | ERROR | [x] Do not append variable name "$contentDirectory" to the type declaration in a member variable comment
30 | ERROR | [x] Do not append variable name "$contentLoader" to the type declaration in a member variable comment
74 | WARNING | [ ] Line exceeds 80 characters; contains 83 characters
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PHPCBF CAN FIX THE 2 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/src/Plugin/yaml_content/process/LayoutSection.php
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FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
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66 | WARNING | Unused variable $index.
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FILE: /var/www/html/dContri/yaml_content/src/Plugin/yaml_content/process/Reference.php
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FOUND 2 ERRORS AFFECTING 2 LINES
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30 | ERROR | Parameter $entity_type_manager is not described in comment
39 | ERROR | Doc comment for parameter $entity_manager does not match actual variable name $entity_type_manager
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FILE: /var/www/html/dContri/yaml_content/src/Plugin/yaml_content/process/File.php
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FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
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35 | WARNING | [x] 'TODO path not set.' should match the format '@todo Fix problem X here.'
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PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/src/Commands/YamlContentCommands.php
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FOUND 1 ERROR AND 1 WARNING AFFECTING 2 LINES
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1 | ERROR | [x] The PHP open tag must be followed by exactly one blank line
94 | WARNING | [ ] \Drupal calls should be avoided in classes, use dependency injection instead
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PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/src/Service/LoadHelper.php
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FOUND 0 ERRORS AND 2 WARNINGS AFFECTING 2 LINES
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90 | WARNING | Line exceeds 80 characters; contains 81 characters
116 | WARNING | Line exceeds 80 characters; contains 81 characters
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FILE: /var/www/html/dContri/yaml_content/src/Service/EntityLoadHelper.php
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FOUND 9 ERRORS AFFECTING 9 LINES
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20 | ERROR | [x] Do not append variable name "$requiresSpecialHandling" to the type declaration in a member variable comment
33 | ERROR | [x] Do not append variable name "$container" to the type declaration in a member variable comment
119 | ERROR | [ ] Missing parameter type
124 | ERROR | [ ] Description for the @return value is missing
174 | ERROR | [ ] Parameter tags must be defined first in a doc comment
206 | ERROR | [ ] Missing parameter type
225 | ERROR | [ ] Missing parameter type
303 | ERROR | [ ] Missing parameter type
333 | ERROR | [ ] Missing parameter type
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PHPCBF CAN FIX THE 2 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/src/Annotation/YamlContentProcess.php
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FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
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13 | WARNING | The class short comment should describe what the class does and not simply repeat the class name
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FILE: /var/www/html/dContri/yaml_content/src/ContentLoader/ContentLoader.php
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FOUND 1 ERROR AFFECTING 1 LINE
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95 | ERROR | Missing short description in doc comment
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FILE: /var/www/html/dContri/yaml_content/yaml_content.drush.inc
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FOUND 1 ERROR AFFECTING 1 LINE
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116 | ERROR | [x] Expected 1 newline at end of file; 2 found
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PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/dContri/yaml_content/README.txt
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FOUND 0 ERRORS AND 3 WARNINGS AFFECTING 3 LINES
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41 | WARNING | Line exceeds 80 characters; contains 84 characters
42 | WARNING | Line exceeds 80 characters; contains 81 characters
46 | WARNING | Line exceeds 80 characters; contains 82 characters
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I have fixed these and have provided the patch.