Program: 80651
Project: 80651
Buggy source:
private static void addContent(MessageContent.Builder builder,List<ExtensionElement> elements,String body,boolean decrypted){
  String outOfBandURL=null;
  for (  ExtensionElement element : elements) {
    if (element instanceof BodyElement) {
      body=((BodyElement)element).getText();
    }
 else     if (element instanceof BitsOfBinary) {
      BitsOfBinary bob=(BitsOfBinary)element;
      String mime=StringUtils.defaultString(bob.getType());
      byte[] bits=bob.getContents();
      if (bits == null)       bits=new byte[0];
      if (mime.isEmpty() || bits.length <= 0)       LOGGER.warning("String_Node_Str" + bob.toXML());
 else       builder.preview(new Preview(bits,mime));
    }
 else     if (element instanceof OutOfBandData) {
      OutOfBandData oobData=(OutOfBandData)element;
      URI url;
      try {
        url=new URI(oobData.getUrl());
      }
 catch (      URISyntaxException ex) {
        LOGGER.log(Level.WARNING,"String_Node_Str",ex);
        url=URI.create("String_Node_Str");
      }
      builder.attachment(new InAttachment(url));
      outOfBandURL=url.toString();
    }
 else     if (element instanceof GroupExtension) {
      GroupExtension group=(GroupExtension)element;
      KonGroupData gid=new KonGroupData(JID.bare(group.getOwner()),group.getID());
      GroupCommand groupCommand=ClientUtils.groupExtensionToGroupCommand(group.getType(),group.getMembers(),group.getSubject()).orElse(null);
      builder.groupData(gid);
      if (groupCommand != null)       builder.groupCommand(groupCommand);
    }
 else {
      if (decrypted || !IGNORED_NAMESPACES.contains(element.getNamespace()))       LOGGER.warning("String_Node_Str" + (element == null ? element : element.toXML().toString()));
    }
  }
  if (body.equals(outOfBandURL))   body="String_Node_Str";
  if (!body.isEmpty())   builder.body(body);
}

Fixed version (ground truth):
private static void addContent(MessageContent.Builder builder,List<ExtensionElement> elements,String body,boolean decrypted){
  String outOfBandURL=null;
  for (  ExtensionElement element : elements) {
    if (element instanceof BodyElement) {
      body=((BodyElement)element).getText();
    }
 else     if (element instanceof BitsOfBinary) {
      BitsOfBinary bob=(BitsOfBinary)element;
      String mime=StringUtils.defaultString(bob.getType());
      byte[] bits=bob.getContents();
      if (bits == null)       bits=new byte[0];
      if (mime.isEmpty() || bits.length <= 0)       LOGGER.warning("String_Node_Str" + bob.toXML());
 else       builder.preview(new Preview(bits,mime));
    }
 else     if (element instanceof OutOfBandData) {
      OutOfBandData oobData=(OutOfBandData)element;
      URI url;
      try {
        url=new URI(oobData.getUrl());
      }
 catch (      URISyntaxException ex) {
        LOGGER.log(Level.WARNING,"String_Node_Str",ex);
        url=URI.create("String_Node_Str");
      }
      builder.attachment(new InAttachment(url));
      outOfBandURL=url.toString();
    }
 else     if (element instanceof GroupExtension) {
      GroupExtension group=(GroupExtension)element;
      KonGroupData gid=new KonGroupData(JID.bare(group.getOwner()),group.getID());
      GroupCommand groupCommand=ClientUtils.groupExtensionToGroupCommand(group.getType(),group.getMembers(),group.getSubject()).orElse(null);
      builder.groupData(gid);
      if (groupCommand != null)       builder.groupCommand(groupCommand);
    }
 else {
      if (decrypted || !IGNORED_NAMESPACES.contains(element.getNamespace()))       LOGGER.warning("String_Node_Str" + (element == null ? null : element.toXML().toString()));
    }
  }
  if (body.equals(outOfBandURL))   body="String_Node_Str";
  if (!body.isEmpty())   builder.body(body);
}