The theme the block is being created in. When creating a new custom block from the block library, the user is redirected to the configure form
public BlockContent::getInstances()
public BlockContent::setTheme($theme)
public BlockContent::createDuplicate()
public BlockContent::setRevisionUser(UserInterface $account)
public BlockContent::postSave(EntityStorageInterface $storage
public BlockContent::getRevisionUserId()
public BlockContent::setRevisionLogMessage($revision_
public BlockContent::getRevisionCreationTime()
public BlockContent::getRevisionUser()
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