private MockSource child(final String streamTypeName) {
            final Map<String, byte[]> typeMap = getFileData().get(meta.getId());
            if (typeMap.containsKey(streamTypeName)) {
                return new MockSource(this, streamTypeName);
            }

            if (InternalStreamTypeNames.BOUNDARY_INDEX.equals(streamTypeName)) {
                return new MockBoundaryStreamSource(this);
            }

            return null;
        }
Gets the output stream for this stream target.
stroom-data/stroom-data-store-mock/src/main/java/stroom/data/store/mock/MockStore.java