Kartik, Since the stack trace refers to TestNG classes, it looks like the Maven part is correct. Maven is finding the TestNG jar and kicking off TestNG.
The stack trace also gives us a clue that TestNG is looking for a number in an XML file where you currently have the string "true." The testng.xml file comes to mind. Then go through any place you have "true" and confirm that is allowed (per the documentation.) One thing I've done a few times was set the verbose attribute to "true" instead of "1". It's a common mistake.