curl --request GET \
  --url https://api.example.com/v1/projects/{project}/databaseGroups

{
  "databaseGroups": [
    {
      "title": "<string>",
      "name": "<string>",
      "databaseExpr": {
        "id": "<string>",
        "constExpr": {
          "nullValue": "NULL_VALUE",
          "boolValue": true,
          "int64Value": "<string>",
          "uint64Value": "<string>",
          "doubleValue": 123,
          "stringValue": "<string>",
          "bytesValue": "<string>",
          "durationValue": "<string>",
          "timestampValue": "2023-11-07T05:31:56Z"
        },
        "identExpr": {
          "name": "<string>"
        },
        "selectExpr": {
          "operand": "<unknown>",
          "field": "<string>",
          "testOnly": true
        },
        "callExpr": {
          "target": "<unknown>",
          "function": "<string>",
          "args": "<array>"
        },
        "listExpr": {
          "elements": "<array>",
          "optionalIndices": [
            123
          ]
        },
        "structExpr": {
          "messageName": "<string>",
          "entries": [
            {
              "id": "<string>",
              "fieldKey": "<string>",
              "mapKey": "<unknown>",
              "value": "<unknown>",
              "optionalEntry": true
            }
          ]
        },
        "comprehensionExpr": {
          "iterVar": "<string>",
          "iterVar2": "<string>",
          "iterRange": "<unknown>",
          "accuVar": "<string>",
          "accuInit": "<unknown>",
          "loopCondition": "<unknown>",
          "loopStep": "<unknown>",
          "result": "<unknown>"
        }
      },
      "matchedDatabases": [
        {
          "name": "<string>"
        }
      ]
    }
  ]
}