title: NullPointerException in java.base/java.util.StringTokenizer.isDelimiter
body: <p>Sometimes I'm getting a NullPointerException in
  java.base/java.util.StringTokenizer.isDelimiter
  but I can't reproduce this consistently.</p>
  <p>Here's the stacktrace:</p>
  <pre><code>java.base/java.util.StringTokenizer.isDelimiter(Unknown Source), 
  java.base/java.util.StringTokenizer.scanToken(Unknown Source), 
  java.base/java.util.StringTokenizer.countTokens(Unknown Source), 
  com.sun.media.imageio.plugins.tiff.TIFFField.createFromMetadataNode(TIFFField.java:476), 
  com.sun.media.imageioimpl.plugins.tiff.TIFFImageMetadata.parseIFD(TIFFImageMetadata.java:1576), 
  com.sun.media.imageioimpl.plugins.tiff.TIFFImageMetadata.mergeNativeTree(TIFFImageMetadata.java:1600), 
  com.sun.media.imageioimpl.plugins.tiff.TIFFImageMetadata.mergeTree(TIFFImageMetadata.java:1624), 
  java.desktop/javax.imageio.metadata.IIOMetadata.setFromTree(Unknown Source)
  </code></pre>
  <p>I'm using this line:</p>
  <pre><code>// metaData is of type: javax.imageio.metadata.IIOMetadata
  // node is of type: org.w3c.dom.Node
  // formatName has value: &quot;com_sun_media_imageio_plugins_tiff_image_1.0&quot;;
  
  metaData.setFromTree(formatName, node);
  </code></pre>
  <p>Could this be a bug in the JVM?
  I'm using Adopt OpenJDK OpenJ9 11.0.4</p>