Firestore/src/V1/UpdateDocumentRequest.php
public function setMask($var)
    {
        GPBUtil::checkMessage($var, \Google\Cloud\Firestore\V1\DocumentMask::class);
        $this->mask = $var;

        return $this;
    }
public function setMask($var)
    {
        GPBUtil::checkMessage($var, \Google\Cloud\Firestore\V1\DocumentMask::class);
        $this->mask = $var;

        return $this;
    }
public function setMask ( $ var ) { GPBUtil :: checkMessage ( $ var , \ Google \ Cloud \ Firestore \ V1 \ DocumentMask :: class ) ; $ this -> mask = $ var ; return $ this ; }
The fields to return. If not set, returns all fields.
If the document has a field that is not present in this mask, that field
will not be returned in the response.

Generated from protobuf field <code>.google.firestore.v1.DocumentMask mask = 3;</code>
@param \Google\Cloud\Firestore\V1\DocumentMask $var
@return $this
The fields to return . If not set returns all fields . If the document has a field that is not present in this mask that field will not be returned in the response .