Filter settings for query string containing only alphanumeric values

[cymed]

When querying an entity such as the one accessed by http://qwc-fulltext-search-service:9090/geom/subclass/?filter=[["id","=","D 48"]], the map viewer calls http://qwc-fulltext-search-service:9090/geom/subclass/?filter=[["id","=",48]] with no quotes if

1. the query is numeric and
2. There are entity entries not only consisting of numeric values only

Expected behaviour:
map viewer calls http://qwc-fulltext-search-service:9090/geom/subclass/?filter=[["id","=","48"]]

this is especially bothersome for queries with trailing zeroes