https://tomcat.apache.org/: Tomcat Connectors and HTTP parser 
public class org.apache.tomcat.util.http.ResponseUtil
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: org.apache.tomcat.util.http.ResponseUtil
  super_class: java.lang.Object
{
  private static final java.lang.String VARY_HEADER;
    descriptor: Ljava/lang/String;
    flags: (0x001a) ACC_PRIVATE, ACC_STATIC, ACC_FINAL
    ConstantValue: "vary"

  private static final java.lang.String VARY_ALL;
    descriptor: Ljava/lang/String;
    flags: (0x001a) ACC_PRIVATE, ACC_STATIC, ACC_FINAL
    ConstantValue: "*"

  private void <init>();
    descriptor: ()V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.apache.tomcat.util.http.ResponseUtil this
         0: .line 37
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 39
            return
        end local 0 // org.apache.tomcat.util.http.ResponseUtil this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    2     0  this  Lorg/apache/tomcat/util/http/ResponseUtil;

  public static void addVaryFieldName(org.apache.tomcat.util.http.MimeHeaders, java.lang.String);
    descriptor: (Lorg/apache/tomcat/util/http/MimeHeaders;Ljava/lang/String;)V
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=3, locals=2, args_size=2
        start local 0 // org.apache.tomcat.util.http.MimeHeaders headers
        start local 1 // java.lang.String name
         0: .line 43
            new org.apache.tomcat.util.http.ResponseUtil$HeaderAdapter
            dup
            aload 0 /* headers */
            invokespecial org.apache.tomcat.util.http.ResponseUtil$HeaderAdapter.<init>:(Lorg/apache/tomcat/util/http/MimeHeaders;)V
            aload 1 /* name */
            invokestatic org.apache.tomcat.util.http.ResponseUtil.addVaryFieldName:(Lorg/apache/tomcat/util/http/ResponseUtil$Adapter;Ljava/lang/String;)V
         1: .line 44
            return
        end local 1 // java.lang.String name
        end local 0 // org.apache.tomcat.util.http.MimeHeaders headers
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    2     0  headers  Lorg/apache/tomcat/util/http/MimeHeaders;
            0    2     1     name  Ljava/lang/String;
    MethodParameters:
         Name  Flags
      headers  
      name     

  public static void addVaryFieldName(jakarta.servlet.http.HttpServletResponse, java.lang.String);
    descriptor: (Ljakarta/servlet/http/HttpServletResponse;Ljava/lang/String;)V
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=3, locals=2, args_size=2
        start local 0 // jakarta.servlet.http.HttpServletResponse response
        start local 1 // java.lang.String name
         0: .line 48
            new org.apache.tomcat.util.http.ResponseUtil$ResponseAdapter
            dup
            aload 0 /* response */
            invokespecial org.apache.tomcat.util.http.ResponseUtil$ResponseAdapter.<init>:(Ljakarta/servlet/http/HttpServletResponse;)V
            aload 1 /* name */
            invokestatic org.apache.tomcat.util.http.ResponseUtil.addVaryFieldName:(Lorg/apache/tomcat/util/http/ResponseUtil$Adapter;Ljava/lang/String;)V
         1: .line 49
            return
        end local 1 // java.lang.String name
        end local 0 // jakarta.servlet.http.HttpServletResponse response
      LocalVariableTable:
        Start  End  Slot      Name  Signature
            0    2     0  response  Ljakarta/servlet/http/HttpServletResponse;
            0    2     1      name  Ljava/lang/String;
    MethodParameters:
          Name  Flags
      response  
      name      

  private static void addVaryFieldName(org.apache.tomcat.util.http.ResponseUtil$Adapter, java.lang.String);
    descriptor: (Lorg/apache/tomcat/util/http/ResponseUtil$Adapter;Ljava/lang/String;)V
    flags: (0x000a) ACC_PRIVATE, ACC_STATIC
    Code:
      stack=3, locals=7, args_size=2
        start local 0 // org.apache.tomcat.util.http.ResponseUtil$Adapter adapter
        start local 1 // java.lang.String name
         0: .line 54
            aload 0 /* adapter */
            ldc "vary"
            invokeinterface org.apache.tomcat.util.http.ResponseUtil$Adapter.getHeaders:(Ljava/lang/String;)Ljava/util/Collection;
            astore 2 /* varyHeaders */
        start local 2 // java.util.Collection varyHeaders
         1: .line 57
            aload 2 /* varyHeaders */
            invokeinterface java.util.Collection.size:()I
            iconst_1
            if_icmpne 3
            aload 2 /* varyHeaders */
            invokeinterface java.util.Collection.iterator:()Ljava/util/Iterator;
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast java.lang.String
            invokevirtual java.lang.String.trim:()Ljava/lang/String;
            ldc "*"
            invokevirtual java.lang.String.equals:(Ljava/lang/Object;)Z
            ifeq 3
         2: .line 59
            return
         3: .line 63
      StackMap locals: java.util.Collection
      StackMap stack:
            aload 2 /* varyHeaders */
            invokeinterface java.util.Collection.size:()I
            ifne 6
         4: .line 64
            aload 0 /* adapter */
            ldc "vary"
            aload 1 /* name */
            invokeinterface org.apache.tomcat.util.http.ResponseUtil$Adapter.addHeader:(Ljava/lang/String;Ljava/lang/String;)V
         5: .line 65
            return
         6: .line 69
      StackMap locals:
      StackMap stack:
            ldc "*"
            aload 1 /* name */
            invokevirtual java.lang.String.trim:()Ljava/lang/String;
            invokevirtual java.lang.String.equals:(Ljava/lang/Object;)Z
            ifeq 9
         7: .line 70
            aload 0 /* adapter */
            ldc "vary"
            ldc "*"
            invokeinterface org.apache.tomcat.util.http.ResponseUtil$Adapter.setHeader:(Ljava/lang/String;Ljava/lang/String;)V
         8: .line 71
            return
         9: .line 79
      StackMap locals:
      StackMap stack:
            new java.util.LinkedHashSet
            dup
            invokespecial java.util.LinkedHashSet.<init>:()V
            astore 3 /* fieldNames */
        start local 3 // java.util.LinkedHashSet fieldNames
        10: .line 81
            aload 2 /* varyHeaders */
            invokeinterface java.util.Collection.iterator:()Ljava/util/Iterator;
            astore 5
            goto 16
      StackMap locals: org.apache.tomcat.util.http.ResponseUtil$Adapter java.lang.String java.util.Collection java.util.LinkedHashSet top java.util.Iterator
      StackMap stack:
        11: aload 5
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast java.lang.String
            astore 4 /* varyHeader */
        start local 4 // java.lang.String varyHeader
        12: .line 82
            new java.io.StringReader
            dup
            aload 4 /* varyHeader */
            invokespecial java.io.StringReader.<init>:(Ljava/lang/String;)V
            astore 6 /* input */
        start local 6 // java.io.StringReader input
        13: .line 84
            aload 6 /* input */
            aload 3 /* fieldNames */
            invokestatic org.apache.tomcat.util.http.parser.TokenList.parseTokenList:(Ljava/io/Reader;Ljava/util/Collection;)Z
            pop
        14: .line 85
            goto 16
      StackMap locals: org.apache.tomcat.util.http.ResponseUtil$Adapter java.lang.String java.util.Collection java.util.LinkedHashSet java.lang.String java.util.Iterator java.io.StringReader
      StackMap stack: java.io.IOException
        15: pop
        end local 6 // java.io.StringReader input
        end local 4 // java.lang.String varyHeader
        16: .line 81
      StackMap locals: org.apache.tomcat.util.http.ResponseUtil$Adapter java.lang.String java.util.Collection java.util.LinkedHashSet top java.util.Iterator
      StackMap stack:
            aload 5
            invokeinterface java.util.Iterator.hasNext:()Z
            ifne 11
        17: .line 90
            aload 3 /* fieldNames */
            ldc "*"
            invokevirtual java.util.LinkedHashSet.contains:(Ljava/lang/Object;)Z
            ifeq 20
        18: .line 92
            aload 0 /* adapter */
            ldc "vary"
            ldc "*"
            invokeinterface org.apache.tomcat.util.http.ResponseUtil$Adapter.setHeader:(Ljava/lang/String;Ljava/lang/String;)V
        19: .line 93
            return
        20: .line 98
      StackMap locals: org.apache.tomcat.util.http.ResponseUtil$Adapter java.lang.String java.util.Collection java.util.LinkedHashSet
      StackMap stack:
            aload 3 /* fieldNames */
            aload 1 /* name */
            invokevirtual java.util.LinkedHashSet.add:(Ljava/lang/Object;)Z
            pop
        21: .line 99
            new java.lang.StringBuilder
            dup
            invokespecial java.lang.StringBuilder.<init>:()V
            astore 4 /* varyHeader */
        start local 4 // java.lang.StringBuilder varyHeader
        22: .line 100
            aload 3 /* fieldNames */
            invokevirtual java.util.LinkedHashSet.iterator:()Ljava/util/Iterator;
            astore 5 /* iter */
        start local 5 // java.util.Iterator iter
        23: .line 102
            aload 4 /* varyHeader */
            aload 5 /* iter */
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast java.lang.String
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            pop
        24: .line 103
            goto 27
        25: .line 104
      StackMap locals: java.lang.StringBuilder java.util.Iterator
      StackMap stack:
            aload 4 /* varyHeader */
            bipush 44
            invokevirtual java.lang.StringBuilder.append:(C)Ljava/lang/StringBuilder;
            pop
        26: .line 105
            aload 4 /* varyHeader */
            aload 5 /* iter */
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast java.lang.String
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            pop
        27: .line 103
      StackMap locals:
      StackMap stack:
            aload 5 /* iter */
            invokeinterface java.util.Iterator.hasNext:()Z
            ifne 25
        28: .line 107
            aload 0 /* adapter */
            ldc "vary"
            aload 4 /* varyHeader */
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            invokeinterface org.apache.tomcat.util.http.ResponseUtil$Adapter.setHeader:(Ljava/lang/String;Ljava/lang/String;)V
        29: .line 108
            return
        end local 5 // java.util.Iterator iter
        end local 4 // java.lang.StringBuilder varyHeader
        end local 3 // java.util.LinkedHashSet fieldNames
        end local 2 // java.util.Collection varyHeaders
        end local 1 // java.lang.String name
        end local 0 // org.apache.tomcat.util.http.ResponseUtil$Adapter adapter
      LocalVariableTable:
        Start  End  Slot         Name  Signature
            0   30     0      adapter  Lorg/apache/tomcat/util/http/ResponseUtil$Adapter;
            0   30     1         name  Ljava/lang/String;
            1   30     2  varyHeaders  Ljava/util/Collection<Ljava/lang/String;>;
           10   30     3   fieldNames  Ljava/util/LinkedHashSet<Ljava/lang/String;>;
           12   16     4   varyHeader  Ljava/lang/String;
           13   16     6        input  Ljava/io/StringReader;
           22   30     4   varyHeader  Ljava/lang/StringBuilder;
           23   30     5         iter  Ljava/util/Iterator<Ljava/lang/String;>;
      Exception table:
        from    to  target  type
          13    14      15  Class java.io.IOException
    MethodParameters:
         Name  Flags
      adapter  
      name     
}
SourceFile: "ResponseUtil.java"
NestMembers:
  org.apache.tomcat.util.http.ResponseUtil$Adapter  org.apache.tomcat.util.http.ResponseUtil$HeaderAdapter  org.apache.tomcat.util.http.ResponseUtil$ResponseAdapter
InnerClasses:
  private abstract Adapter = org.apache.tomcat.util.http.ResponseUtil$Adapter of org.apache.tomcat.util.http.ResponseUtil
  private final HeaderAdapter = org.apache.tomcat.util.http.ResponseUtil$HeaderAdapter of org.apache.tomcat.util.http.ResponseUtil
  private final ResponseAdapter = org.apache.tomcat.util.http.ResponseUtil$ResponseAdapter of org.apache.tomcat.util.http.ResponseUtil