boolean issue fix

[LeiZhang-Hunter]

fix defaults boolean

test config:

pipelines:
  - name: local
    sources:
      - type: file
        name: demo
        ack:
          enable: false
        paths:
          - /tmp/log/*.log
        fields:
          topic: "loggie"
    sink:
      type: dev
      printEvents: true
      codec:
        pretty: true

results:
file.config.ack.enable = false