ERROR Source option 1.5 is no longer supported. Use 1.6 or later

Question

It all happens when I was trying to build a springboot application by ./mvnw clean install

When I first run the install command, it runs into followin

Answer 1

I got this error: "Source option 5 is no longer supported. Use 6 or later" after I changed the pom.xml

7

to

11

Later to realise the property was used with a dash insteal of a dot:

  ${java-version}
  ${java-version}

(swearings), I replaced the dot with a dash and the error went away:

11