Java: Generated @Pattern annotation does not encode the pattern

My spec contains a pattern validation for a schema:

components:
  schemas:
    myCustomId:
      type: string
      pattern: '^[A-Z]\d{9}$'

When generating code the beanValidationCore.mustache uses the literal pattern from the Spec which leads to compile errors because the \ character is not escaped in the generated Java String.

I know I can just put the properly escaped pattern into the spec. But from a modeling/specification point of view I don't want to deal with Java specifics. IMHO that's the concern of the code generator for the platform.

Start with the generated Java annotation handling in beanValidationCore.mustache and compare it with the supplied schema pattern. Verify the generated Java string compiles while preserving the intended regular expression, then check generated output for the example schema.