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.io.CharSource$AsByteSource extends com.google.common.io.ByteSource
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: com.google.common.io.CharSource$AsByteSource
  super_class: com.google.common.io.ByteSource
{
  final java.nio.charset.Charset charset;
    descriptor: Ljava/nio/charset/Charset;
    flags: (0x0010) ACC_FINAL

  final com.google.common.io.CharSource this$0;
    descriptor: Lcom/google/common/io/CharSource;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  void <init>(com.google.common.io.CharSource, java.nio.charset.Charset);
    descriptor: (Lcom/google/common/io/CharSource;Ljava/nio/charset/Charset;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=3, args_size=3
        start local 0 // com.google.common.io.CharSource$AsByteSource this
        start local 2 // java.nio.charset.Charset charset
         0: .line 499
            aload 0 /* this */
            aload 1
            putfield com.google.common.io.CharSource$AsByteSource.this$0:Lcom/google/common/io/CharSource;
            aload 0 /* this */
            invokespecial com.google.common.io.ByteSource.<init>:()V
         1: .line 500
            aload 0 /* this */
            aload 2 /* charset */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast java.nio.charset.Charset
            putfield com.google.common.io.CharSource$AsByteSource.charset:Ljava/nio/charset/Charset;
         2: .line 501
            return
        end local 2 // java.nio.charset.Charset charset
        end local 0 // com.google.common.io.CharSource$AsByteSource this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    3     0     this  Lcom/google/common/io/CharSource$AsByteSource;
            0    3     2  charset  Ljava/nio/charset/Charset;
    MethodParameters:
         Name  Flags
      this$0   final
      charset  

  public com.google.common.io.CharSource asCharSource(java.nio.charset.Charset);
    descriptor: (Ljava/nio/charset/Charset;)Lcom/google/common/io/CharSource;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.google.common.io.CharSource$AsByteSource this
        start local 1 // java.nio.charset.Charset charset
         0: .line 505
            aload 1 /* charset */
            aload 0 /* this */
            getfield com.google.common.io.CharSource$AsByteSource.charset:Ljava/nio/charset/Charset;
            invokevirtual java.nio.charset.Charset.equals:(Ljava/lang/Object;)Z
            ifeq 2
         1: .line 506
            aload 0 /* this */
            getfield com.google.common.io.CharSource$AsByteSource.this$0:Lcom/google/common/io/CharSource;
            areturn
         2: .line 508
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            aload 1 /* charset */
            invokespecial com.google.common.io.ByteSource.asCharSource:(Ljava/nio/charset/Charset;)Lcom/google/common/io/CharSource;
            areturn
        end local 1 // java.nio.charset.Charset charset
        end local 0 // com.google.common.io.CharSource$AsByteSource this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    3     0     this  Lcom/google/common/io/CharSource$AsByteSource;
            0    3     1  charset  Ljava/nio/charset/Charset;
    MethodParameters:
         Name  Flags
      charset  

  public java.io.InputStream openStream();
    descriptor: ()Ljava/io/InputStream;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=1, args_size=1
        start local 0 // com.google.common.io.CharSource$AsByteSource this
         0: .line 513
            new com.google.common.io.ReaderInputStream
            dup
            aload 0 /* this */
            getfield com.google.common.io.CharSource$AsByteSource.this$0:Lcom/google/common/io/CharSource;
            invokevirtual com.google.common.io.CharSource.openStream:()Ljava/io/Reader;
            aload 0 /* this */
            getfield com.google.common.io.CharSource$AsByteSource.charset:Ljava/nio/charset/Charset;
            sipush 8192
            invokespecial com.google.common.io.ReaderInputStream.<init>:(Ljava/io/Reader;Ljava/nio/charset/Charset;I)V
            areturn
        end local 0 // com.google.common.io.CharSource$AsByteSource this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/io/CharSource$AsByteSource;
    Exceptions:
      throws java.io.IOException

  public java.lang.String toString();
    descriptor: ()Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=1, args_size=1
        start local 0 // com.google.common.io.CharSource$AsByteSource this
         0: .line 518
            new java.lang.StringBuilder
            dup
            aload 0 /* this */
            getfield com.google.common.io.CharSource$AsByteSource.this$0:Lcom/google/common/io/CharSource;
            invokevirtual java.lang.Object.toString:()Ljava/lang/String;
            invokestatic java.lang.String.valueOf:(Ljava/lang/Object;)Ljava/lang/String;
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            ldc ".asByteSource("
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            aload 0 /* this */
            getfield com.google.common.io.CharSource$AsByteSource.charset:Ljava/nio/charset/Charset;
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/Object;)Ljava/lang/StringBuilder;
            ldc ")"
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            areturn
        end local 0 // com.google.common.io.CharSource$AsByteSource this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/io/CharSource$AsByteSource;
}
SourceFile: "CharSource.java"
NestHost: com.google.common.io.CharSource
InnerClasses:
  private final AsByteSource = com.google.common.io.CharSource$AsByteSource of com.google.common.io.CharSource