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.ByteSource$ConcatenatedByteSource extends com.google.common.io.ByteSource
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: com.google.common.io.ByteSource$ConcatenatedByteSource
  super_class: com.google.common.io.ByteSource
{
  final java.lang.Iterable<? extends com.google.common.io.ByteSource> sources;
    descriptor: Ljava/lang/Iterable;
    flags: (0x0010) ACC_FINAL
    Signature: Ljava/lang/Iterable<+Lcom/google/common/io/ByteSource;>;

  void <init>(java.lang.Iterable<? extends com.google.common.io.ByteSource>);
    descriptor: (Ljava/lang/Iterable;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.google.common.io.ByteSource$ConcatenatedByteSource this
        start local 1 // java.lang.Iterable sources
         0: .line 673
            aload 0 /* this */
            invokespecial com.google.common.io.ByteSource.<init>:()V
         1: .line 674
            aload 0 /* this */
            aload 1 /* sources */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast java.lang.Iterable
            putfield com.google.common.io.ByteSource$ConcatenatedByteSource.sources:Ljava/lang/Iterable;
         2: .line 675
            return
        end local 1 // java.lang.Iterable sources
        end local 0 // com.google.common.io.ByteSource$ConcatenatedByteSource this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    3     0     this  Lcom/google/common/io/ByteSource$ConcatenatedByteSource;
            0    3     1  sources  Ljava/lang/Iterable<+Lcom/google/common/io/ByteSource;>;
    Signature: (Ljava/lang/Iterable<+Lcom/google/common/io/ByteSource;>;)V
    MethodParameters:
         Name  Flags
      sources  

  public java.io.InputStream openStream();
    descriptor: ()Ljava/io/InputStream;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=1, args_size=1
        start local 0 // com.google.common.io.ByteSource$ConcatenatedByteSource this
         0: .line 679
            new com.google.common.io.MultiInputStream
            dup
            aload 0 /* this */
            getfield com.google.common.io.ByteSource$ConcatenatedByteSource.sources:Ljava/lang/Iterable;
            invokeinterface java.lang.Iterable.iterator:()Ljava/util/Iterator;
            invokespecial com.google.common.io.MultiInputStream.<init>:(Ljava/util/Iterator;)V
            areturn
        end local 0 // com.google.common.io.ByteSource$ConcatenatedByteSource this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/io/ByteSource$ConcatenatedByteSource;
    Exceptions:
      throws java.io.IOException

  public boolean isEmpty();
    descriptor: ()Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=3, args_size=1
        start local 0 // com.google.common.io.ByteSource$ConcatenatedByteSource this
         0: .line 684
            aload 0 /* this */
            getfield com.google.common.io.ByteSource$ConcatenatedByteSource.sources:Ljava/lang/Iterable;
            invokeinterface java.lang.Iterable.iterator:()Ljava/util/Iterator;
            astore 2
            goto 4
      StackMap locals: com.google.common.io.ByteSource$ConcatenatedByteSource top java.util.Iterator
      StackMap stack:
         1: aload 2
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast com.google.common.io.ByteSource
            astore 1 /* source */
        start local 1 // com.google.common.io.ByteSource source
         2: .line 685
            aload 1 /* source */
            invokevirtual com.google.common.io.ByteSource.isEmpty:()Z
            ifne 4
         3: .line 686
            iconst_0
            ireturn
        end local 1 // com.google.common.io.ByteSource source
         4: .line 684
      StackMap locals:
      StackMap stack:
            aload 2
            invokeinterface java.util.Iterator.hasNext:()Z
            ifne 1
         5: .line 689
            iconst_1
            ireturn
        end local 0 // com.google.common.io.ByteSource$ConcatenatedByteSource this
      LocalVariableTable:
        Start  End  Slot    Name  Signature
            0    6     0    this  Lcom/google/common/io/ByteSource$ConcatenatedByteSource;
            2    4     1  source  Lcom/google/common/io/ByteSource;
    Exceptions:
      throws java.io.IOException

  public com.google.common.base.Optional<java.lang.Long> sizeIfKnown();
    descriptor: ()Lcom/google/common/base/Optional;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=6, args_size=1
        start local 0 // com.google.common.io.ByteSource$ConcatenatedByteSource this
         0: .line 694
            aload 0 /* this */
            getfield com.google.common.io.ByteSource$ConcatenatedByteSource.sources:Ljava/lang/Iterable;
            instanceof java.util.Collection
            ifne 2
         1: .line 700
            invokestatic com.google.common.base.Optional.absent:()Lcom/google/common/base/Optional;
            areturn
         2: .line 702
      StackMap locals:
      StackMap stack:
            lconst_0
            lstore 1 /* result */
        start local 1 // long result
         3: .line 703
            aload 0 /* this */
            getfield com.google.common.io.ByteSource$ConcatenatedByteSource.sources:Ljava/lang/Iterable;
            invokeinterface java.lang.Iterable.iterator:()Ljava/util/Iterator;
            astore 4
            goto 11
      StackMap locals: com.google.common.io.ByteSource$ConcatenatedByteSource long top java.util.Iterator
      StackMap stack:
         4: aload 4
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast com.google.common.io.ByteSource
            astore 3 /* source */
        start local 3 // com.google.common.io.ByteSource source
         5: .line 704
            aload 3 /* source */
            invokevirtual com.google.common.io.ByteSource.sizeIfKnown:()Lcom/google/common/base/Optional;
            astore 5 /* sizeIfKnown */
        start local 5 // com.google.common.base.Optional sizeIfKnown
         6: .line 705
            aload 5 /* sizeIfKnown */
            invokevirtual com.google.common.base.Optional.isPresent:()Z
            ifne 8
         7: .line 706
            invokestatic com.google.common.base.Optional.absent:()Lcom/google/common/base/Optional;
            areturn
         8: .line 708
      StackMap locals: com.google.common.io.ByteSource$ConcatenatedByteSource long com.google.common.io.ByteSource java.util.Iterator com.google.common.base.Optional
      StackMap stack:
            lload 1 /* result */
            aload 5 /* sizeIfKnown */
            invokevirtual com.google.common.base.Optional.get:()Ljava/lang/Object;
            checkcast java.lang.Long
            invokevirtual java.lang.Long.longValue:()J
            ladd
            lstore 1 /* result */
         9: .line 709
            lload 1 /* result */
            lconst_0
            lcmp
            ifge 11
        10: .line 715
            ldc 9223372036854775807
            invokestatic java.lang.Long.valueOf:(J)Ljava/lang/Long;
            invokestatic com.google.common.base.Optional.of:(Ljava/lang/Object;)Lcom/google/common/base/Optional;
            areturn
        end local 5 // com.google.common.base.Optional sizeIfKnown
        end local 3 // com.google.common.io.ByteSource source
        11: .line 703
      StackMap locals: com.google.common.io.ByteSource$ConcatenatedByteSource long top java.util.Iterator
      StackMap stack:
            aload 4
            invokeinterface java.util.Iterator.hasNext:()Z
            ifne 4
        12: .line 718
            lload 1 /* result */
            invokestatic java.lang.Long.valueOf:(J)Ljava/lang/Long;
            invokestatic com.google.common.base.Optional.of:(Ljava/lang/Object;)Lcom/google/common/base/Optional;
            areturn
        end local 1 // long result
        end local 0 // com.google.common.io.ByteSource$ConcatenatedByteSource this
      LocalVariableTable:
        Start  End  Slot         Name  Signature
            0   13     0         this  Lcom/google/common/io/ByteSource$ConcatenatedByteSource;
            3   13     1       result  J
            5   11     3       source  Lcom/google/common/io/ByteSource;
            6   11     5  sizeIfKnown  Lcom/google/common/base/Optional<Ljava/lang/Long;>;
    Signature: ()Lcom/google/common/base/Optional<Ljava/lang/Long;>;

  public long size();
    descriptor: ()J
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=5, args_size=1
        start local 0 // com.google.common.io.ByteSource$ConcatenatedByteSource this
         0: .line 723
            lconst_0
            lstore 1 /* result */
        start local 1 // long result
         1: .line 724
            aload 0 /* this */
            getfield com.google.common.io.ByteSource$ConcatenatedByteSource.sources:Ljava/lang/Iterable;
            invokeinterface java.lang.Iterable.iterator:()Ljava/util/Iterator;
            astore 4
            goto 6
      StackMap locals: com.google.common.io.ByteSource$ConcatenatedByteSource long top java.util.Iterator
      StackMap stack:
         2: aload 4
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast com.google.common.io.ByteSource
            astore 3 /* source */
        start local 3 // com.google.common.io.ByteSource source
         3: .line 725
            lload 1 /* result */
            aload 3 /* source */
            invokevirtual com.google.common.io.ByteSource.size:()J
            ladd
            lstore 1 /* result */
         4: .line 726
            lload 1 /* result */
            lconst_0
            lcmp
            ifge 6
         5: .line 732
            ldc 9223372036854775807
            lreturn
        end local 3 // com.google.common.io.ByteSource source
         6: .line 724
      StackMap locals:
      StackMap stack:
            aload 4
            invokeinterface java.util.Iterator.hasNext:()Z
            ifne 2
         7: .line 735
            lload 1 /* result */
            lreturn
        end local 1 // long result
        end local 0 // com.google.common.io.ByteSource$ConcatenatedByteSource this
      LocalVariableTable:
        Start  End  Slot    Name  Signature
            0    8     0    this  Lcom/google/common/io/ByteSource$ConcatenatedByteSource;
            1    8     1  result  J
            3    6     3  source  Lcom/google/common/io/ByteSource;
    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.ByteSource$ConcatenatedByteSource this
         0: .line 740
            new java.lang.StringBuilder
            dup
            ldc "ByteSource.concat("
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            aload 0 /* this */
            getfield com.google.common.io.ByteSource$ConcatenatedByteSource.sources:Ljava/lang/Iterable;
            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.ByteSource$ConcatenatedByteSource this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/io/ByteSource$ConcatenatedByteSource;
}
SourceFile: "ByteSource.java"
NestHost: com.google.common.io.ByteSource
InnerClasses:
  private final ConcatenatedByteSource = com.google.common.io.ByteSource$ConcatenatedByteSource of com.google.common.io.ByteSource