code: public void validateProposedIndex( ExecutionContext context,
                                         IndexDefinition defn,
                                         NodeTypes.Supplier nodeTypesSupplier,
                                         Problems problems ) {
          //nothing by default
      }
docs: Validate the proposed index definition, and use the supplied problems to report any issues that will prevent this provider
  from creating and using an index with the given definition.
  <p>
  This should only be implemented if the provider has any particular validation requirements (for example it doesn't support
  multiple columns or certain index types). The repository will perform for all index definitions some basic validations
  via {@link #validateDefaultColumnTypes(ExecutionContext, IndexDefinition, Problems)}
  </p>
  
  @param context the execution context in which to perform the validation; never null
  @param defn the proposed index definition; never null
  @param nodeTypesSupplier the supplier for the NodeTypes object that contains information about the currently-registered
  node types; never null
  @param problems the problems that should be used to report any issues with the index definition; never null