MatchName in an expression that is matched against the name of each
element in the feature set.
op
string required
Op is the operator to be applied.
enum: In, NotIn, InRegexp, Exists, DoesNotExist, Gt, Lt, GtLt, IsTrue, IsFalse
value
[]string
Value is the list of values that the operand evaluates the input
against. Value should be empty if the operator is Exists, DoesNotExist,
IsTrue or IsFalse. Value should contain exactly one element if the
operator is Gt or Lt and exactly two elements if the operator is GtLt.
In other cases Value should contain at least one element.