Merge pull request #2689 from pdbain-ibm/nestmates

Make MethodType.lastParameter() public

jcl/src/java.base/share/classes/java/lang/invoke/MethodHandle.java

@@ -679,11 +679,8 @@ public MethodHandle withVarargs(boolean isVarArityNeeded) throws IllegalArgument
 		if (isVarArityNeeded) {
 			/* Convert the handle if initially not with variable arity */
 			if (!this.isVarargsCollector()) {
-				Class<?> lastClass = null;
-				try {
-					/* An exception is thrown if the MethodType has no arguments */
-					lastClass = this.type.lastParameterType();
-				} catch(RuntimeException e) {
+				Class<?> lastClass = this.type.lastParameterType();
+				if (void.class == lastClass) { /* there were no arguments */
 					throw new IllegalArgumentException();
 				}
 				/* IllegalArgumentException will be thrown out from asVarargsCollector 

jcl/src/java.base/share/classes/java/lang/invoke/MethodType.java

@@ -901,14 +901,21 @@ public Class<?> returnType(){
 		return returnType;
 	}
 
-	/* Return the last class in the parameterType array.
+	/**
+	 * Return the last class in the parameterType array.
 	 * This is equivalent to:
 	 * 		type.parameterType(type.parameterCount() - 1)
-	 * Will throw ArrayIndexOutOfBounds on bad indexes.  This is a subclass of IndexOutOfBoundsException
-	 * so this is valid when JCKs expect certain exceptions.
+	 * @return class of final parameter, or void.class if there are no parameters
 	 */
-	/* package */ Class<?> lastParameterType() {
-		 return arguments[arguments.length - 1];
+	/*[IF Java10]*/
+	public
+	/*[ENDIF]*/
+	Class<?> lastParameterType() {
+		Class<?> result = void.class;
+		if (arguments.length > 0) {
+			result = arguments[arguments.length - 1];
+		}
+		return result;
 	}
 
 	/**