cd
cd projectsjavaprojA
mvn clean

(define invocation-method (lambda () (system "c:\test.bat")))
;; capture output
(string-split (with-output-to-string invocation-method) "n")

'mvn' is not recognized as an internal or external command,
operable program or batch file.
'("r"
  "C:\Users\aviad>cd\r"
  "r"
  "C:\>cd projects\java\projAr"
  "r"
  "C:\projects\java\projA>mvn clean r")