Wrapper to allow span queries to participate in composite single-field span queries by
lying about their search field. The span field masking query maps to Lucene’s
SpanFieldMaskingQuery
This can be used to support queries like span-near or span-or across different fields,
which is not ordinarily permitted.
Span field masking query is invaluable in conjunction with multi-fields when same content
is indexed with multiple analyzers. For instance we could index a field with the standard
analyzer which breaks text up into words, and again with the english analyzer which stems words
into their root form.
Note: as span field masking query returns the masked field, scoring will be done using the
norms of the field name supplied. This may lead to unexpected scoring behavior.