http://netty.io/netty-all/: Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers and clients. (The Netty Project) 
class io.netty.util.internal.SystemPropertyUtil$1 implements java.security.PrivilegedAction<java.lang.String>
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: io.netty.util.internal.SystemPropertyUtil$1
  super_class: java.lang.Object
{
  private final java.lang.String val$key;
    descriptor: Ljava/lang/String;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  void <init>(java.lang.String);
    descriptor: (Ljava/lang/String;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // io.netty.util.internal.SystemPropertyUtil$1 this
         0: .line 71
            aload 0 /* this */
            aload 1
            putfield io.netty.util.internal.SystemPropertyUtil$1.val$key:Ljava/lang/String;
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // io.netty.util.internal.SystemPropertyUtil$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lio/netty/util/internal/SystemPropertyUtil$1;
    MethodParameters:
         Name  Flags
      val$key  final

  public java.lang.String run();
    descriptor: ()Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // io.netty.util.internal.SystemPropertyUtil$1 this
         0: .line 74
            aload 0 /* this */
            getfield io.netty.util.internal.SystemPropertyUtil$1.val$key:Ljava/lang/String;
            invokestatic java.lang.System.getProperty:(Ljava/lang/String;)Ljava/lang/String;
            areturn
        end local 0 // io.netty.util.internal.SystemPropertyUtil$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lio/netty/util/internal/SystemPropertyUtil$1;

  public java.lang.Object run();
    descriptor: ()Ljava/lang/Object;
    flags: (0x1041) ACC_PUBLIC, ACC_BRIDGE, ACC_SYNTHETIC
    Code:
      stack=1, locals=1, args_size=1
         0: .line 1
            aload 0
            invokevirtual io.netty.util.internal.SystemPropertyUtil$1.run:()Ljava/lang/String;
            areturn
      LocalVariableTable:
        Start  End  Slot  Name  Signature
}
Signature: Ljava/lang/Object;Ljava/security/PrivilegedAction<Ljava/lang/String;>;
SourceFile: "SystemPropertyUtil.java"
EnclosingMethod: io.netty.util.internal.SystemPropertyUtil.get:(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
NestHost: io.netty.util.internal.SystemPropertyUtil
InnerClasses:
  io.netty.util.internal.SystemPropertyUtil$1