Add FluxKontextMultiReferenceLatentMethod node. (#9356)

This node is only useful if someone trains the kontext model to properly
use multiple reference images via the index method.

The default is the offset method which feeds the multiple images like if
they were stitched together as one. This method works with the current
flux kontext model.

comfy_extras/nodes_flux.py

@@ -100,9 +100,28 @@ class FluxKontextImageScale:
         return (image, )
 
 
+class FluxKontextMultiReferenceLatentMethod:
+    @classmethod
+    def INPUT_TYPES(s):
+        return {"required": {
+            "conditioning": ("CONDITIONING", ),
+            "reference_latents_method": (("offset", "index"), ),
+            }}
+
+    RETURN_TYPES = ("CONDITIONING",)
+    FUNCTION = "append"
+    EXPERIMENTAL = True
+
+    CATEGORY = "advanced/conditioning/flux"
+
+    def append(self, conditioning, reference_latents_method):
+        c = node_helpers.conditioning_set_values(conditioning, {"reference_latents_method": reference_latents_method})
+        return (c, )
+
 NODE_CLASS_MAPPINGS = {
     "CLIPTextEncodeFlux": CLIPTextEncodeFlux,
     "FluxGuidance": FluxGuidance,
     "FluxDisableGuidance": FluxDisableGuidance,
     "FluxKontextImageScale": FluxKontextImageScale,
+    "FluxKontextMultiReferenceLatentMethod": FluxKontextMultiReferenceLatentMethod,
 }