UMLR — ReadStructuralFeatureAction

This issue concerns the ReadStructuralFeatureAction. This action reads the values of a structural feature, in order if the structural feature is ordered. According to the sepcification, the multiplicity of the structural feature must be compatible with the multiplicity of the output pin, so the output pin will contain all the values of the structural feature. There is no way to read the value of a single element from a multi-valued structural feature without reading all its values. Adding an input pin (readAt) to ReadStructuralFeatureAction would allow this. This input pin would represent the index of the value we want to read in the structural feature. This issue stands for ReadVariableAction as well.