public void clear() {
        pooledByteBufferOutputStream.clear();
        writeMetaDataPadding();
        typeId = null;
        fullBuffer = null;
        valueBuffer = null;
    }
<pre>{@code
<type ID int><hash code long><value bytes................>
}</pre>
<p>
Allows us to build a {@link ByteBuffer} backed value from a stream of data and at the end
insert the type information and a hash of the value into the buffer. {@link PooledByteBufferOutputStream}
is used to expand to accommodate any size of data.
stroom-pipeline/src/main/java/stroom/pipeline/refdata/store/StagingValueOutputStream.java