Find All Property Names in hl7 Message

Have you tried GetContentArray() from EnsLib.HL7.Message? Then you could do something similar to Testing Virtual Property Paths in the Terminal. For example,

ClassMethod PrintPropertyPaths(){
 set string="MSH|^~\&|MIHIN PATIENT GEN|1.2.3.4.5.9.99.999.9999.1004||2.16.840.1.113883.3.1481|20200103000000+0000||ADT^A01^ADT_A01|1092|P|2.6|1091|||||||||Windward General Hospital"_$C(13,10)_
            "EVN||20200110000000+0000|||||1.2.3.4.5.9.99.999.9999.1004"_
            "PID|1|3170|44c8a6bba5c743538e476a813256959b^^^^CKS~000003170^^^^SS||Santana^Pearl||19900609|F||2054-5^Black or African American^HL70005|364 NE Oak Circle^^Trenton^MI^48183||||||||000003170|||N^Not Hispanic or Latino^HL70189|||||||20200110000000+0000|N"_$C(13,10)_
            "PD1|||Windward General Hospital^^^^^^^^^1.2.3.4.5.9.99.999.9999.1004|9999992221^Johnston^Karl^^^^^^^^^^NPI^^^^^^^^MD"_$C(13,10)_
            "PV1|1|I|^^67^1.2.3.4.5.9.99.999.9999.1004||||9999992221^Johnston^Karl^^^^^^^^^^NPI||||||||||||17a5e3aa59a34ad5af017998278a5eb5||||||||||||||||||&HOME^20200110000000+0000|||||||20200103000000DG1|1||Z34.90^Normal pregnancy^I10||20200103000000+0000|F|^Become_Pregnant"_$C(13,10)_
            "IN1|1|1772^STATE HEALTH PLAN|1027|MEDICAID||||||||||||Santana^Pearl^Gladys|||364 NE Oak Circle^^Trenton^MI^48183"_$C(13,10)
 set target=##class(EnsLib.HL7.Message).ImportFromString(string,.status)
 if 'status {do $system.Status.DisplayError(status) quit}
 set target.DocType="2.6:ADT_A01"
 
 do target.GetContentArray(.propertyPaths,, target.DocType)
 for i=1:1:propertyPaths {
   for j=1:1:propertyPaths(i) {
     w i, ".", j, propertyPaths(i,j, "name"), !
   }
 }}