This method creates a constraint for a given Rebar Constrained Handle Tag. Will throw exception if used for Shape Driven Rebar. 
   Namespace:   Autodesk.Revit.DB.Structure  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 22.0.0.0 (22.1.0.0) 
  Since:  2018 
Syntax
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Parameters
- handle
-  Type:  Autodesk.Revit.DB.Structure RebarConstrainedHandle  
 The handle of the rebar that will be constrained.
- targetReferences
-  Type:  System.Collections.Generic IList   Reference  
 The references to which the rebar handle will be constrained. This collection must contain one or more references to faces of elements that can host rebar.
- isConstraintToCover
-  Type:  System Boolean  
 If true the RebarConstraintType will be set to ToCover, otherwise RebarConstraintType will be set to FixedDistanceToHostFace.
- offsetValue
-  Type:  System Double  
 The distance from references to the rebar handle.
Return Value
Returns the newly created RebarConstraint.Exceptions
| Exception | Condition | 
|---|---|
| Autodesk.Revit.Exceptions ArgumentException | Constrained rebar is a shape driven rebar element. -or- handle is no longer valid. -or- targetReferences is empty. -or- targetReferences do not represent faces from structurals that can host rebar. | 
| Autodesk.Revit.Exceptions ArgumentNullException | A non-optional argument was null |