An interpretation of Thelonious Monk’s “Mysterioso” scrubbed of shadowy ambiguities is emblematic of the tone of guitarist John Stein’s nineteenth album. Clean and precise, Next Gen: Jazz for my Grandchildren sounds like the product of a music teacher. Stein retired from the Berklee College of Music in 2020 after spending 36 years as a professor at the Boston institution. Yet Next Gen isn’t antiseptic. Along with bassist Ed Lucie and drummer Mike Connors, the Kansas City native applies polite swing to standards and original compositions dedicated to his grandchildren. It’s only natural that grandfatherly jazz should be sweet, gentle and suffused with love.