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

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!

Start by comparing the source flow across router.go, controller.go, validator.go, and param.go with the default ActiveThreatModelSource in TainterPath.ql. Reproduce the difference between Quick Evaluation and TaintTracking::Global, then inspect the custom GinContextGetSource query and its references to val.Get, req, and c. Done means the intended source is recognized in the global data flow.

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