public void setMetadataWriteFilter(MetadataWriteFilter writeFilter) {
        this.writeFilter = writeFilter;
        this.writeFilter.filterExisting(metadata);
    }
Sets the writeFilter that is called before {@link #set(String, String)}
{@link #set(String, String[])}, {@link #add(String, String)},
{@link #add(String, String[])}.  The default is {@link #ACCEPT_ALL}.

This is intended for expert use only.  Some parsers rely on metadata
during the parse, and if the metadata they need is excluded, they
will not function properly.

@param writeFilter
@since 2.4.0
tika-core/src/main/java/org/apache/tika/metadata/Metadata.java