https://github.com/google/guava/guava: Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more. 
final class com.google.common.base.CharMatcher$BitSetMatcher extends com.google.common.base.CharMatcher$NamedFastMatcher
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: com.google.common.base.CharMatcher$BitSetMatcher
  super_class: com.google.common.base.CharMatcher$NamedFastMatcher
{
  private final java.util.BitSet table;
    descriptor: Ljava/util/BitSet;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private void <init>(java.util.BitSet, java.lang.String);
    descriptor: (Ljava/util/BitSet;Ljava/lang/String;)V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=2, locals=3, args_size=3
        start local 0 // com.google.common.base.CharMatcher$BitSetMatcher this
        start local 1 // java.util.BitSet table
        start local 2 // java.lang.String description
         0: .line 987
            aload 0 /* this */
            aload 2 /* description */
            invokespecial com.google.common.base.CharMatcher$NamedFastMatcher.<init>:(Ljava/lang/String;)V
         1: .line 988
            aload 1 /* table */
            invokevirtual java.util.BitSet.length:()I
            bipush 64
            iadd
            aload 1 /* table */
            invokevirtual java.util.BitSet.size:()I
            if_icmpge 3
         2: .line 989
            aload 1 /* table */
            invokevirtual java.util.BitSet.clone:()Ljava/lang/Object;
            checkcast java.util.BitSet
            astore 1 /* table */
         3: .line 992
      StackMap locals: com.google.common.base.CharMatcher$BitSetMatcher java.util.BitSet java.lang.String
      StackMap stack:
            aload 0 /* this */
            aload 1 /* table */
            putfield com.google.common.base.CharMatcher$BitSetMatcher.table:Ljava/util/BitSet;
         4: .line 993
            return
        end local 2 // java.lang.String description
        end local 1 // java.util.BitSet table
        end local 0 // com.google.common.base.CharMatcher$BitSetMatcher this
      LocalVariableTable:
        Start  End  Slot         Name  Signature
            0    5     0         this  Lcom/google/common/base/CharMatcher$BitSetMatcher;
            0    5     1        table  Ljava/util/BitSet;
            0    5     2  description  Ljava/lang/String;
    MethodParameters:
             Name  Flags
      table        
      description  

  public boolean matches(char);
    descriptor: (C)Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.google.common.base.CharMatcher$BitSetMatcher this
        start local 1 // char c
         0: .line 997
            aload 0 /* this */
            getfield com.google.common.base.CharMatcher$BitSetMatcher.table:Ljava/util/BitSet;
            iload 1 /* c */
            invokevirtual java.util.BitSet.get:(I)Z
            ireturn
        end local 1 // char c
        end local 0 // com.google.common.base.CharMatcher$BitSetMatcher this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/base/CharMatcher$BitSetMatcher;
            0    1     1     c  C
    MethodParameters:
      Name  Flags
      c     

  void setBits(java.util.BitSet);
    descriptor: (Ljava/util/BitSet;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.google.common.base.CharMatcher$BitSetMatcher this
        start local 1 // java.util.BitSet bitSet
         0: .line 1002
            aload 1 /* bitSet */
            aload 0 /* this */
            getfield com.google.common.base.CharMatcher$BitSetMatcher.table:Ljava/util/BitSet;
            invokevirtual java.util.BitSet.or:(Ljava/util/BitSet;)V
         1: .line 1003
            return
        end local 1 // java.util.BitSet bitSet
        end local 0 // com.google.common.base.CharMatcher$BitSetMatcher this
      LocalVariableTable:
        Start  End  Slot    Name  Signature
            0    2     0    this  Lcom/google/common/base/CharMatcher$BitSetMatcher;
            0    2     1  bitSet  Ljava/util/BitSet;
    MethodParameters:
        Name  Flags
      bitSet  
}
SourceFile: "CharMatcher.java"
NestHost: com.google.common.base.CharMatcher
InnerClasses:
  private final BitSetMatcher = com.google.common.base.CharMatcher$BitSetMatcher of com.google.common.base.CharMatcher
  abstract NamedFastMatcher = com.google.common.base.CharMatcher$NamedFastMatcher of com.google.common.base.CharMatcher
    RuntimeInvisibleAnnotations: 
      com.google.common.annotations.GwtIncompatible()