1. i checked the internet and stackoverflow almost all threads and none of them had my issue mentioned.
2. Steps to reproduce 

• install the plugin
• restart jenkins
• create a freestyle jenkins project
• in Build environment tab i have checked the checkbox "Mask passwords and regexes (and enable global passwords)"
• I have not provided any name/password pairs or regex
• in the jenkins settings for this plugin i have not selected , "Enable Mask Passwords for ALL BUILDS" and did not provide any global password pair or regexes. but below that I have selected only 1 checkbox "Password Parameter" and clicked "Apply" and save.

I have expecting only the password parameters in my build will be masked ? 

But i noticed my string parameters were also getting masked automatically .. 

any idea if this is a configuration issue ?