public void clearFieldsByURI(URI fileURI) {
        for (Iterator<Map.Entry<Symbol, FieldIndexEntry>> it = database.entrySet().iterator(); it.hasNext(); ) {
            Map.Entry<Symbol, FieldIndexEntry> entry = it.next();
            if (entry.getKey().fileURIEquals(fileURI)) {
                it.remove();
            }
        }
    }
FieldIndex
For storing metadata about fields.
It is owned by a SchemaIndex, so there is a one-to-one correspondence
integration/schema-language-server/language-server/src/main/java/ai/vespa/schemals/index/FieldIndex.java