Case statement ambiguous with timeOfDay values

Our rules for the Case statement use colons to separate the condition from the value-if-true and value-if-false:

caseMethodCallExpr = "case" OPEN BWS boolCommonExpr BWS COLON BWS commonExpr BWS 
                        *( COMMA BWS boolCommonExpr BWS COLON BWS commonExpr BWS ) CLOSE

However, timeOfDay also uses colons to separate the parts of a time of day value, including optional seconds:

timeOfDayValueInUrl = hour COLON minute [ COLON second [ "." fractionalSeconds ] ]

That means that, for certain time of day values, the case statement could be ambiguous. i.e.;

case(CreatedTime eq 10:20:15:10:10,15:20)

which could legally be parsed any of the following ways:
  if CreatedTime eq 10:20 then 15:10:10 otherwise 15:20
  if CreatedTime eq 10:20:15 then 10:10 otherwise 15:20

Note that the user could differentiate between these by inserting whitespace before/after the separators separating the case parameters:
  case(CreatedTime eq 10:20 : 15:10:10 : 15:20)
  case(CreatedTime eq 10:20:15 : 10:10 : 15:20)