Remove confusing “by reference” wording from data-model

If I understand Thiemo’s explanation correctly, this is essentially a
PHP 4 concern surviving in our code base: in PHP 4, objects were by
default passed “by value” (i.e., by shallow copy, just like arrays still
are), and to get a shared mutable object (or just to avoid the cost of
copying objects all the time) you would have to explicitly pass them
around “by reference” instead. Since PHP 5, objects are always passed by
reference, so this distinction is no longer relevant.

Change-Id: Ic08d1de5d743e174d8664a06dc65ce44d48c1d67

Author: lucaswerkmeister

src/Statement/StatementListHolder.php

@@ -7,7 +7,7 @@
  *
  * @since 3.0
  * @deprecated since 5.1, will be removed in favor of StatementListProvider, which
- *  gives the guarantee to return an object by reference. Changes to that object change the entity.
+ *  gives the guarantee to return a mutable object. Changes to that object change the entity.
  *
  * @license GPL-2.0-or-later
  * @author Thiemo Kreuz

src/Statement/StatementListProvider.php

@@ -4,7 +4,7 @@
 
 /**
  * Common interface for classes (typically Entities) that contain a StatementList. Implementations
- * must guarantee this returns the original, mutable object by reference.
+ * must guarantee this returns the original, mutable object.
  *
  * @since 2.2.0
  *
@@ -14,7 +14,7 @@
 interface StatementListProvider {
 
 	/**
-	 * This is guaranteed to return the original, mutable object by reference.
+	 * This is guaranteed to return the original, mutable object.
 	 *
 	 * @return StatementList
 	 */

src/Term/AliasesProvider.php

@@ -4,7 +4,7 @@
 
 /**
  * Common interface for classes (typically Entities) that contain an AliasGroupList. Implementations
- * must guarantee this returns the original, mutable object by reference.
+ * must guarantee this returns the original, mutable object.
  *
  * @since 4.1
  *
@@ -14,7 +14,7 @@
 interface AliasesProvider {
 
 	/**
-	 * This is guaranteed to return the original, mutable object by reference.
+	 * This is guaranteed to return the original, mutable object.
 	 *
 	 * @return AliasGroupList
 	 */

src/Term/DescriptionsProvider.php

@@ -4,8 +4,7 @@
 
 /**
  * Common interface for classes (typically Entities) that contain a TermList, representing
- * descriptions. Implementations must guarantee this returns the original, mutable object by
- * reference.
+ * descriptions. Implementations must guarantee this returns the original, mutable object.
  *
  * @since 4.1
  *
@@ -15,7 +14,7 @@
 interface DescriptionsProvider {
 
 	/**
-	 * This is guaranteed to return the original, mutable object by reference.
+	 * This is guaranteed to return the original, mutable object.
 	 *
 	 * @return TermList
 	 */

src/Term/FingerprintProvider.php

@@ -4,7 +4,7 @@
 
 /**
  * Common interface for classes (typically Entities) that contain a Fingerprint. Implementations
- * must guarantee this returns the original, mutable object by reference.
+ * must guarantee this returns the original, mutable object.
  *
  * @since 0.7.3
  *
@@ -14,7 +14,7 @@
 interface FingerprintProvider {
 
 	/**
-	 * This is guaranteed to return the original, mutable object by reference.
+	 * This is guaranteed to return the original, mutable object.
 	 *
 	 * @return Fingerprint
 	 */

src/Term/LabelsProvider.php

@@ -4,7 +4,7 @@
 
 /**
  * Common interface for classes (typically Entities) that contain a TermList, representing labels.
- * Implementations must guarantee this returns the original, mutable object by reference.
+ * Implementations must guarantee this returns the original, mutable object.
  *
  * @since 4.1
  *
@@ -14,7 +14,7 @@
 interface LabelsProvider {
 
 	/**
-	 * This is guaranteed to return the original, mutable object by reference.
+	 * This is guaranteed to return the original, mutable object.
 	 *
 	 * @return TermList
 	 */