To add properties file spring please follow below steps:
Create resources folder inside your project as source folder
Create sample properties file sample.properties inside resources folder and add some content in it sample below:
invalid-key=The CAPTCHA Service public key is incorrect.invalid-parameters=The CAPTCHA Service was invoked with incorrect parameters.unknown-error=The CAPTCHA Service returned an unknown error.incorrect-captcha-sol=The letters in the graphic were entered incorrectly. Please try again.NotBlank.captcha.response=The letters in the graphic were entered incorrectly. Please try again.
In your spring context XML file add below bean tag: