Improve docs of LiveLiteral

Also remove transitive closure from calls

Author: atorralba

java/ql/lib/semmle/code/java/frameworks/android/Compose.qll

@@ -14,10 +14,19 @@ class LiveLiteral extends MethodAccess {
     not this.getEnclosingCallable() instanceof LiveLiteralMethod
   }
 
-  /** Gets the constant value that backs this live literal. */
+  /**
+   * Live literal classes consist of the following:
+   * - A private field holding the constant value that backs this live literal.
+   * - A private getter to access the constant value.
+   * - A public getter that either calls the private getter and returns its result or,
+   * if live literals are activated, returns the value of a dynamic state object that is initialized with
+   * the constant value.
+   *
+   * This predicate gets the constant value held by the private field.
+   */
   CompileTimeConstantExpr getValue() {
     result =
-      any(ReturnStmt r | this.getMethod().calls*(r.getEnclosingCallable()))
+      any(ReturnStmt r | this.getMethod().calls(r.getEnclosingCallable()))
           .getResult()
           .(VarAccess)
           .getVariable()