General issue Go. Why isn't the following code recognized as a source in a global data stream?

[Weirdokky]

Why isn't the following code recognized as a source in a global data stream? If I want to identify this source in the global data stream, how should I write my QL?

Here's the code context：

//router.go
func RegisterServers(group *gin.RouterGroup) {
	group.POST("/abc/test", val.Validate[*param.TestParam], controller.TestReadFile)
}

//controller.go
func TestReadFile(c *gin.Context) {
	req := val.Get[*param.TestParam](c)
	cleanPath := req.Path
	file, err := os.Open(cleanPath)
	if err != nil {
		if os.IsNotExist(err) {
			c.JSON(http.StatusNotFound, gin.H{"error": "file not found"})
		} else {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to open file"})
		}
		return
	}
......
}

//validator.go
package val
func Validate[T any](ctx *gin.Context) {
	var req T
	if err := ctx.ShouldBindJSON(&req); err != nil {
		ctx.JSON(http.StatusBadRequest, gin.H{"code": constant.UnknownErrorCode, "msg": util.GetErrorText(constant.UnknownErrorCode)})
		ctx.Abort()
		return
	}
	ctx.Set("params", req)
	ctx.Next()
}

func Get[T any](ctx *gin.Context) T {
	return ctx.MustGet("params").(T)
}

//param.go
package param

type TestParam struct {
	Path string `json:"filepath"`
}

I found that the default "ActiveThreatModelSource" in the official rule "TainterPath.ql" is not recognizable as a source by the above code.
Here's the code I wrote to try to add a new class about this kind of source, and I use "req" from "req.Path" as the source, although the result can be recognized when "Quick Evaluation" is used, but when it is run in the whole "TaintTracking::Global", it cannot be recognized that there is a problem with this "controller.go".

class GinContextGetSource extends DataFlow::Node {
  GinContextGetSource() {
    exists(Function asmGet, CallExpr call |
    asmGet.hasQualifiedName("project/router/val", "Get")
    and call.getTarget() =  asmGet
    and call.getEnclosingFunction() = this.asExpr().getEnclosingFunction()
    and this.asExpr().toString() = "req"
    and this.asExpr().getEnclosingFunction().getAParameter().toString() = "c"
    )
  }
}

I need to address this issue urgently. Because the routing and controller parts of the entire Gin project that I am currently responsible for are developed in this form, the global data flow in each of my official rules cannot be identified in any of the sources
Thank you so much!