Issue #3045039 by heddn: code standards

migrate_example_advanced/README.txt

src/DataFetcherPluginBase.php

src/Event/MigratePrepareRowEvent.php

src/Plugin/migrate/process/Dom.php

src/Plugin/migrate/process/EntityLookup.php

src/Plugin/migrate/process/FileBlob.php

src/Plugin/migrate/process/SkipOnValue.php

src/Plugin/migrate/process/StrReplace.php

src/Plugin/migrate_plus/authentication/OAuth2.php

src/Plugin/migrate_plus/data_parser/Soap.php