Fix description and improve predicate name of VarWrite.

Author: smowton

java/ql/lib/semmle/code/java/Expr.qll

@@ -1850,7 +1850,7 @@ class VarWrite extends VarAccess {
   VarWrite() { this.isVarWrite() }
 
   /**
-   * Gets the right-hand side of the assignment that executes this variable write.
+   * Gets a source of the assignment that executes this variable write.
    *
    * For assignments using the `=` operator, the source expression
    * is simply the RHS of the assignment.
@@ -1859,7 +1859,10 @@ class VarWrite extends VarAccess {
    * (such as (`+=`), both the RHS and the LHS of the compound assignment
    * are source expressions of the assignment.
    */
-  Expr getRhs() { exists(Assignment e | e.getDest() = this and e.getSource() = result) }
+  Expr getASource() { exists(Assignment e | e.getDest() = this and e.getSource() = result) }
+
+  /** DEPRECATED: (Inaccurately-named) alias for `getASource` */
+  deprecated Expr getRhs() { result = this.getASource() }
 }
 
 /** DEPRECATED: Alias for `VarWrite`. */

java/ql/lib/semmle/code/java/dataflow/internal/FlowSummaryImplSpecific.qll

@@ -333,7 +333,7 @@ predicate interpretInputSpecific(string c, InterpretNode mid, InterpretNode n) {
   exists(FieldWrite fw |
     c = "" and
     fw.getField() = mid.asElement() and
-    n.asNode().asExpr() = fw.getRhs()
+    n.asNode().asExpr() = fw.getASource()
   )
 }