@Field
    public void setMappings(Map<String, String> mappings) {
        for (Map.Entry<String, String> e : mappings.entrySet()) {
            this.mappings.put(e.getKey(), e.getValue());
        }
    }
If this is <code>true</code> (default), this means that only the fields that
have a "from" value in the mapper will be passed through.  Otherwise,
this will pass through all keys/values and mutate the keys
that exist in the mappings.

@param excludeUnmapped
tika-core/src/main/java/org/apache/tika/metadata/filter/FieldNameMappingFilter.java