rs available in the 
 runtime environment.
 
 <p> Implementations must be thread-safe.

 <p> Note that the <code>getPersistenceProviders</code> method can potentially
 be called many times: it is recommended that the implementation
 of this method make use of caching.</div>
<dl>
<dt><span class="simpleTagLabel">Since:</span></dt>
<dd>2.0</dd>
<dt><span class="seeLabel">See Also:</span></dt>
<dd><a href="PersistenceProvider.html" title="interface in javax.persistence.spi"><code>PersistenceProvider</code></a>