Removed (Serializable)EntityId::isForeign

the concept of "entities from a foreign repositories"
has not been integrated into Wikibase.

Bug: T291823
Depends-On: I54e4e12f4cda2a3966c727c45a953ba17dc11a73
Change-Id: I6895bc5ebe50eadc2a584c8c72547f79f1053fac

Author: manicki

src/Entity/SerializableEntityId.php

@@ -149,15 +149,6 @@ public function getLocalPart() {
 		return $this->localPart;
 	}
 
-	/**
-	 * Returns true iff SerializableEntityId::getRepositoryName returns a non-empty string.
-	 *
-	 * @return bool
-	 */
-	public function isForeign() {
-		return $this->repositoryName !== '';
-	}
-
 	/**
 	 * @param string $id
 	 *

tests/unit/Entity/EntityIdTest.php

@@ -101,12 +101,6 @@ public function testReturnTypeOfToString( EntityId $id ) {
 		$this->assertIsString( $id->__toString() );
 	}
 
-	public function testIsForeign() {
-		$this->assertFalse( ( new ItemId( 'Q42' ) )->isForeign() );
-		$this->assertFalse( ( new ItemId( ':Q42' ) )->isForeign() );
-		$this->assertFalse( ( new NumericPropertyId( ':P42' ) )->isForeign() );
-	}
-
 	/**
 	 * @dataProvider instanceProvider
 	 */