http://www.javassist.org/: Javassist (JAVA programming ASSISTant) makes Java bytecode manipulation simple. It is a class library for editing bytecodes in Java. (Shigeru Chiba, www.javassist.org) 
final class javassist.JarDirClassPath implements javassist.ClassPath
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: javassist.JarDirClassPath
  super_class: java.lang.Object
{
  javassist.JarClassPath[] jars;
    descriptor: [Ljavassist/JarClassPath;
    flags: (0x0000) 

  void <init>(java.lang.String);
    descriptor: (Ljava/lang/String;)V
    flags: (0x0000) 
    Code:
      stack=6, locals=4, args_size=2
        start local 0 // javassist.JarDirClassPath this
        start local 1 // java.lang.String dirName
         0: .line 89
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 90
            new java.io.File
            dup
            aload 1 /* dirName */
            invokespecial java.io.File.<init>:(Ljava/lang/String;)V
            new javassist.JarDirClassPath$1
            dup
            aload 0 /* this */
            invokespecial javassist.JarDirClassPath$1.<init>:(Ljavassist/JarDirClassPath;)V
            invokevirtual java.io.File.listFiles:(Ljava/io/FilenameFilter;)[Ljava/io/File;
            astore 2 /* files */
        start local 2 // java.io.File[] files
         2: .line 98
            aload 2 /* files */
            ifnull 9
         3: .line 99
            aload 0 /* this */
            aload 2 /* files */
            arraylength
            anewarray javassist.JarClassPath
            putfield javassist.JarDirClassPath.jars:[Ljavassist/JarClassPath;
         4: .line 100
            iconst_0
            istore 3 /* i */
        start local 3 // int i
         5: goto 8
         6: .line 101
      StackMap locals: javassist.JarDirClassPath java.lang.String java.io.File[] int
      StackMap stack:
            aload 0 /* this */
            getfield javassist.JarDirClassPath.jars:[Ljavassist/JarClassPath;
            iload 3 /* i */
            new javassist.JarClassPath
            dup
            aload 2 /* files */
            iload 3 /* i */
            aaload
            invokevirtual java.io.File.getPath:()Ljava/lang/String;
            invokespecial javassist.JarClassPath.<init>:(Ljava/lang/String;)V
            aastore
         7: .line 100
            iinc 3 /* i */ 1
      StackMap locals:
      StackMap stack:
         8: iload 3 /* i */
            aload 2 /* files */
            arraylength
            if_icmplt 6
        end local 3 // int i
         9: .line 103
      StackMap locals:
      StackMap stack:
            return
        end local 2 // java.io.File[] files
        end local 1 // java.lang.String dirName
        end local 0 // javassist.JarDirClassPath this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0   10     0     this  Ljavassist/JarDirClassPath;
            0   10     1  dirName  Ljava/lang/String;
            2   10     2    files  [Ljava/io/File;
            5    9     3        i  I
    Exceptions:
      throws javassist.NotFoundException
    MethodParameters:
         Name  Flags
      dirName  

  public java.io.InputStream openClassfile(java.lang.String);
    descriptor: (Ljava/lang/String;)Ljava/io/InputStream;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=4, args_size=2
        start local 0 // javassist.JarDirClassPath this
        start local 1 // java.lang.String classname
         0: .line 107
            aload 0 /* this */
            getfield javassist.JarDirClassPath.jars:[Ljavassist/JarClassPath;
            ifnull 8
         1: .line 108
            iconst_0
            istore 2 /* i */
        start local 2 // int i
         2: goto 7
         3: .line 109
      StackMap locals: int
      StackMap stack:
            aload 0 /* this */
            getfield javassist.JarDirClassPath.jars:[Ljavassist/JarClassPath;
            iload 2 /* i */
            aaload
            aload 1 /* classname */
            invokevirtual javassist.JarClassPath.openClassfile:(Ljava/lang/String;)Ljava/io/InputStream;
            astore 3 /* is */
        start local 3 // java.io.InputStream is
         4: .line 110
            aload 3 /* is */
            ifnull 6
         5: .line 111
            aload 3 /* is */
            areturn
        end local 3 // java.io.InputStream is
         6: .line 108
      StackMap locals:
      StackMap stack:
            iinc 2 /* i */ 1
      StackMap locals:
      StackMap stack:
         7: iload 2 /* i */
            aload 0 /* this */
            getfield javassist.JarDirClassPath.jars:[Ljavassist/JarClassPath;
            arraylength
            if_icmplt 3
        end local 2 // int i
         8: .line 114
      StackMap locals:
      StackMap stack:
            aconst_null
            areturn
        end local 1 // java.lang.String classname
        end local 0 // javassist.JarDirClassPath this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    9     0       this  Ljavassist/JarDirClassPath;
            0    9     1  classname  Ljava/lang/String;
            2    8     2          i  I
            4    6     3         is  Ljava/io/InputStream;
    Exceptions:
      throws javassist.NotFoundException
    MethodParameters:
           Name  Flags
      classname  

  public java.net.URL find(java.lang.String);
    descriptor: (Ljava/lang/String;)Ljava/net/URL;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=4, args_size=2
        start local 0 // javassist.JarDirClassPath this
        start local 1 // java.lang.String classname
         0: .line 119
            aload 0 /* this */
            getfield javassist.JarDirClassPath.jars:[Ljavassist/JarClassPath;
            ifnull 8
         1: .line 120
            iconst_0
            istore 2 /* i */
        start local 2 // int i
         2: goto 7
         3: .line 121
      StackMap locals: int
      StackMap stack:
            aload 0 /* this */
            getfield javassist.JarDirClassPath.jars:[Ljavassist/JarClassPath;
            iload 2 /* i */
            aaload
            aload 1 /* classname */
            invokevirtual javassist.JarClassPath.find:(Ljava/lang/String;)Ljava/net/URL;
            astore 3 /* url */
        start local 3 // java.net.URL url
         4: .line 122
            aload 3 /* url */
            ifnull 6
         5: .line 123
            aload 3 /* url */
            areturn
        end local 3 // java.net.URL url
         6: .line 120
      StackMap locals:
      StackMap stack:
            iinc 2 /* i */ 1
      StackMap locals:
      StackMap stack:
         7: iload 2 /* i */
            aload 0 /* this */
            getfield javassist.JarDirClassPath.jars:[Ljavassist/JarClassPath;
            arraylength
            if_icmplt 3
        end local 2 // int i
         8: .line 126
      StackMap locals:
      StackMap stack:
            aconst_null
            areturn
        end local 1 // java.lang.String classname
        end local 0 // javassist.JarDirClassPath this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    9     0       this  Ljavassist/JarDirClassPath;
            0    9     1  classname  Ljava/lang/String;
            2    8     2          i  I
            4    6     3        url  Ljava/net/URL;
    MethodParameters:
           Name  Flags
      classname  
}
SourceFile: "ClassPoolTail.java"
NestMembers:
  javassist.JarDirClassPath$1
InnerClasses:
  javassist.JarDirClassPath$1