merge bitmpas:
[
  {
    "type": "block-dirty-bitmap-add",
    "data": {
      "node": "libvirt-4-format",
      "name": "current",
      "persistent": true,
      "disabled": false,
      "granularity": 65536
    }
  },
  {
    "type": "block-dirty-bitmap-merge",
    "data": {
      "node": "libvirt-4-format",
      "target": "current",
      "bitmaps": [
        {
          "node": "libvirt-1-format",
          "name": "current"
        },
        {
          "node": "libvirt-4-format",
          "name": "libvirt-tmp-activewrite"
        }
      ]
    }
  },
  {
    "type": "block-dirty-bitmap-add",
    "data": {
      "node": "libvirt-4-format",
      "name": "c",
      "persistent": true,
      "disabled": false,
      "granularity": 65536
    }
  },
  {
    "type": "block-dirty-bitmap-merge",
    "data": {
      "node": "libvirt-4-format",
      "target": "c",
      "bitmaps": [
        {
          "node": "libvirt-1-format",
          "name": "c"
        },
        {
          "node": "libvirt-2-format",
          "name": "c"
        },
        {
          "node": "libvirt-3-format",
          "name": "c"
        },
        {
          "node": "libvirt-4-format",
          "name": "libvirt-tmp-activewrite"
        }
      ]
    }
  },
  {
    "type": "block-dirty-bitmap-add",
    "data": {
      "node": "libvirt-4-format",
      "name": "b",
      "persistent": true,
      "disabled": false,
      "granularity": 65536
    }
  },
  {
    "type": "block-dirty-bitmap-merge",
    "data": {
      "node": "libvirt-4-format",
      "target": "b",
      "bitmaps": [
        {
          "node": "libvirt-1-format",
          "name": "b"
        },
        {
          "node": "libvirt-2-format",
          "name": "b"
        },
        {
          "node": "libvirt-3-format",
          "name": "b"
        },
        {
          "node": "libvirt-4-format",
          "name": "libvirt-tmp-activewrite"
        }
      ]
    }
  },
  {
    "type": "block-dirty-bitmap-merge",
    "data": {
      "node": "libvirt-4-format",
      "target": "a",
      "bitmaps": [
        {
          "node": "libvirt-1-format",
          "name": "a"
        },
        {
          "node": "libvirt-2-format",
          "name": "a"
        },
        {
          "node": "libvirt-3-format",
          "name": "a"
        },
        {
          "node": "libvirt-4-format",
          "name": "libvirt-tmp-activewrite"
        }
      ]
    }
  },
  {
    "type": "block-dirty-bitmap-add",
    "data": {
      "node": "libvirt-4-format",
      "name": "d",
      "persistent": true,
      "disabled": false,
      "granularity": 65536
    }
  },
  {
    "type": "block-dirty-bitmap-merge",
    "data": {
      "node": "libvirt-4-format",
      "target": "d",
      "bitmaps": [
        {
          "node": "libvirt-1-format",
          "name": "d"
        },
        {
          "node": "libvirt-2-format",
          "name": "d"
        },
        {
          "node": "libvirt-4-format",
          "name": "libvirt-tmp-activewrite"
        }
      ]
    }
  },
  {
    "type": "block-dirty-bitmap-remove",
    "data": {
      "node": "libvirt-4-format",
      "name": "libvirt-tmp-activewrite"
    }
  }
]