IsNil in pdata causes panic: nil pointer dereference

[pavolloffay]

Describe the bug

IsNil methods from pdata package cause panic: nil pointer dereference.

Steps to reproduce

func TestNil(t *testing.T) {
	rs := pdata.Resource{}
	assert.Equal(t, true, rs.IsNil())
}

What did you expect to see?

Not panic either false or true.

What did you see instead?

panic

What version did you use?

What config did you use?

Environment

Additional context

cc @tigrannajaryan

[pavolloffay]

The method logic should be for instance

func (ms Resource) IsNil() bool {
	if ms.orig == nil {
		return true
	}
	return *ms.orig == nil
}

[tigrannajaryan]

rs := pdata.Resource{}

This is not a valid usage as it is described in the comments for pdata.Resource:

// Must use NewResource function to create new instances.
// Important: zero-initialized instance is not valid for use.
type Resource struct {

[pavolloffay]

This is not a valid usage as it is described in the comments for pdata.Resource:

How does the consumer of the resource/pdata structs know that the struct is zero initialized? There should be an API to check for that.