Update a Specific PCI Header

{
  "CmmActionCode": null,
  "CmmAllowance": "N",
  "CmmAprvFlag": "N",
  "CmmAutoCalcMarkupFlag": "N",
  "CmmBchNum": null,
  "CmmBiditemFlag": null,
  "CmmBillCatCode": null,
  "CmmBillCode": null,
  "CmmBillMethCode": "D",
  "CmmBillName": null,
  "CmmBillPhsCode": null,
  "CmmBillRevisAmt": null,
  "CmmCalcProjAmtMethod": "A",
  "CmmChgSentToOwnerDate": null,
  "CmmChgSignedByOwnerDate": null,
  "CmmClassCode": "E",
  "CmmClvValueCode1": null,
  "CmmClvValueCode2": null,
  "CmmClvValueCode3": null,
  "CmmClvValueCode4": null,
  "CmmClvValueCode5": null,
  "CmmClvValueCode6": null,
  "CmmCode": "EXT0123",
  "CmmCompCode": "001",
  "CmmCtrlJobCode": "ALL",
  "CmmCycleNum": null,
  "CmmDueToOwnerDate": null,
  "CmmEffectiveEndDate": null,
  "CmmEffectiveStartDate": null,
  "CmmFundsourceCode": null,
  "CmmGlobalUpdateDate": "2023-01-31T21:16:52Z",
  "CmmImpactDays": null,
  "CmmInvCode": null,
  "CmmIuCreateDate": "2023-01-31T21:16:52Z",
  "CmmIuUpdateDate": null,
  "CmmJobCode": "14001",
  "CmmLumpsumFlag": null,
  "CmmName": "Test PCI",
  "CmmOrigCmmCode": null,
  "CmmOrigOwnerAllowanceAmt": null,
  "CmmOwnerAllowanceAmt": null,
  "CmmOwnerChgCode": null,
  "CmmPendFlag": "P",
  "CmmPmFlag": "Y",
  "CmmPmObjectCode": null,
  "CmmPostContrFlag": "N",
  "CmmPostDate": null,
  "CmmPostDateDummy": null,
  "CmmPostingFlag": "UNPOSTED",
  "CmmPrepostStatCode": "PENDING",
  "CmmPropIssuedToOwnerDate": null,
  "CmmPropSignedByOwnerDate": null,
  "CmmReasonText": null,
  "CmmRefCmmCode": null,
  "CmmRefDate": "2023-11-11",
  "CmmRfqDueDate": null,
  "CmmRfqLimitAmt": null,
  "CmmRfqProceedFlag": null,
  "CmmScopeDesc": null,
  "CmmSourceText": null,
  "CmmSrcId": null,
  "CmmStatCode": null,
  "CmmStatCodeUpdateDate": null,
  "CmmTypeCode": "EXT",
  "CmmUpdPcComplFlag": "Y",
  "CmmUpdProjAmtFlag": null,
  "CmmUser": "CMICUSER",
  "CmmVUuid": "F396762021727DDEE05316821FACD0CF",
  "CmmWorkflowStatus": null,
  "links": [
    {
      "rel": "self",
      "href": "http://mobtest.cmiccloudr12.com:80/cmictestrti/cm-rest-api/rest/1/cmmast/F396762021727DDEE05316821FACD0CF",
      "name": "cmmast",
      "kind": "item"
    },
    {
      "rel": "canonical",
      "href": "http://mobtest.cmiccloudr12.com:80/cmictestrti/cm-rest-api/rest/1/cmmast/F396762021727DDEE05316821FACD0CF",
      "name": "cmmast",
      "kind": "item"
    }
  ]
}