https://eclipse.org/jetty/jetty-util: Utility classes for Jetty (Webtide) 
class org.eclipse.jetty.util.IO$ClosedIS extends java.io.InputStream
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: org.eclipse.jetty.util.IO$ClosedIS
  super_class: java.io.InputStream
{
  private void <init>();
    descriptor: ()V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.eclipse.jetty.util.IO$ClosedIS this
         0: .line 561
            aload 0 /* this */
            invokespecial java.io.InputStream.<init>:()V
            return
        end local 0 // org.eclipse.jetty.util.IO$ClosedIS this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/eclipse/jetty/util/IO$ClosedIS;

  public int read();
    descriptor: ()I
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.eclipse.jetty.util.IO$ClosedIS this
         0: .line 566
            iconst_m1
            ireturn
        end local 0 // org.eclipse.jetty.util.IO$ClosedIS this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/eclipse/jetty/util/IO$ClosedIS;
    Exceptions:
      throws java.io.IOException
}
SourceFile: "IO.java"
NestHost: org.eclipse.jetty.util.IO
InnerClasses:
  private ClosedIS = org.eclipse.jetty.util.IO$ClosedIS of org.eclipse.jetty.util.IO