Collect mime type data correctly for all URIs added to ClipData

import libcore.io.IoUtils;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.HashSet;

import java.util.List;

/**

     */

    public @Nullable ClipData getClipDataForDocuments(List<DocumentInfo> docs) {

        final ContentResolver resolver = mContext.getContentResolver();

        final String[] mimeTypes = getMimeTypes(resolver, docs);

        ClipData clipData = null;

        for (DocumentInfo doc : docs) {

            final Uri uri = DocumentsContract.buildDocumentUri(doc.authority, doc.documentId);

            if (clipData == null) {

                // TODO: figure out what this string should be.

                // Currently it is not displayed anywhere in the UI, but this might change.

                final String label = "";

                clipData = ClipData.newUri(resolver, label, uri);

                clipData = new ClipData(label, mimeTypes, new ClipData.Item(doc.derivedUri));

            } else {

                // TODO: update list of mime types in ClipData.

                clipData.addItem(new ClipData.Item(uri));

                clipData.addItem(new ClipData.Item(doc.derivedUri));

            }

        }

        return clipData;

    }

    private static String[] getMimeTypes(ContentResolver resolver, List<DocumentInfo> docs) {

        final HashSet<String> mimeTypes = new HashSet<>();

        for (DocumentInfo doc : docs) {

            assert(doc != null);

            assert(doc.derivedUri != null);

            final Uri uri = doc.derivedUri;

            if ("content".equals(uri.getScheme())) {

                mimeTypes.add(resolver.getType(uri));

                final String[] streamTypes = resolver.getStreamTypes(uri, "*/*");

                if (streamTypes != null) {

                    mimeTypes.addAll(Arrays.asList(streamTypes));

                }

            }

        }

        return mimeTypes.toArray(new String[0]);

    }

    public void clipDocuments(List<DocumentInfo> docs) {

        ClipData data = getClipDataForDocuments(docs);

        mClipboard.setPrimaryClip(data);