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. 
class com.google.common.collect.Multimaps$MapMultimap$1 extends com.google.common.collect.Sets$ImprovedAbstractSet<V>
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: com.google.common.collect.Multimaps$MapMultimap$1
  super_class: com.google.common.collect.Sets$ImprovedAbstractSet
{
  final com.google.common.collect.Multimaps$MapMultimap this$1;
    descriptor: Lcom/google/common/collect/Multimaps$MapMultimap;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  private final java.lang.Object val$key;
    descriptor: Ljava/lang/Object;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  void <init>(com.google.common.collect.Multimaps$MapMultimap, java.lang.Object);
    descriptor: (Lcom/google/common/collect/Multimaps$MapMultimap;Ljava/lang/Object;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=3, args_size=3
        start local 0 // com.google.common.collect.Multimaps$MapMultimap$1 this
         0: .line 1132
            aload 0 /* this */
            aload 1
            putfield com.google.common.collect.Multimaps$MapMultimap$1.this$1:Lcom/google/common/collect/Multimaps$MapMultimap;
            aload 0 /* this */
            aload 2
            putfield com.google.common.collect.Multimaps$MapMultimap$1.val$key:Ljava/lang/Object;
            aload 0 /* this */
            invokespecial com.google.common.collect.Sets$ImprovedAbstractSet.<init>:()V
            return
        end local 0 // com.google.common.collect.Multimaps$MapMultimap$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/collect/Multimaps$MapMultimap$1;
    MethodParameters:
         Name  Flags
      this$0   final
      val$key  final

  public java.util.Iterator<V> iterator();
    descriptor: ()Ljava/util/Iterator;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=1, args_size=1
        start local 0 // com.google.common.collect.Multimaps$MapMultimap$1 this
         0: .line 1135
            new com.google.common.collect.Multimaps$MapMultimap$1$1
            dup
            aload 0 /* this */
            aload 0 /* this */
            getfield com.google.common.collect.Multimaps$MapMultimap$1.val$key:Ljava/lang/Object;
            invokespecial com.google.common.collect.Multimaps$MapMultimap$1$1.<init>:(Lcom/google/common/collect/Multimaps$MapMultimap$1;Ljava/lang/Object;)V
            areturn
        end local 0 // com.google.common.collect.Multimaps$MapMultimap$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/collect/Multimaps$MapMultimap$1;
    Signature: ()Ljava/util/Iterator<TV;>;

  public int size();
    descriptor: ()I
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=1, args_size=1
        start local 0 // com.google.common.collect.Multimaps$MapMultimap$1 this
         0: .line 1163
            aload 0 /* this */
            getfield com.google.common.collect.Multimaps$MapMultimap$1.this$1:Lcom/google/common/collect/Multimaps$MapMultimap;
            getfield com.google.common.collect.Multimaps$MapMultimap.map:Ljava/util/Map;
            aload 0 /* this */
            getfield com.google.common.collect.Multimaps$MapMultimap$1.val$key:Ljava/lang/Object;
            invokeinterface java.util.Map.containsKey:(Ljava/lang/Object;)Z
            ifeq 1
            iconst_1
            goto 2
      StackMap locals:
      StackMap stack:
         1: iconst_0
      StackMap locals:
      StackMap stack: int
         2: ireturn
        end local 0 // com.google.common.collect.Multimaps$MapMultimap$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    3     0  this  Lcom/google/common/collect/Multimaps$MapMultimap$1;

  static com.google.common.collect.Multimaps$MapMultimap access$0(com.google.common.collect.Multimaps$MapMultimap$1);
    descriptor: (Lcom/google/common/collect/Multimaps$MapMultimap$1;)Lcom/google/common/collect/Multimaps$MapMultimap;
    flags: (0x1008) ACC_STATIC, ACC_SYNTHETIC
    Code:
      stack=1, locals=1, args_size=1
         0: .line 1132
            aload 0
            getfield com.google.common.collect.Multimaps$MapMultimap$1.this$1:Lcom/google/common/collect/Multimaps$MapMultimap;
            areturn
      LocalVariableTable:
        Start  End  Slot  Name  Signature
}
Signature: Lcom/google/common/collect/Sets$ImprovedAbstractSet<TV;>;
SourceFile: "Multimaps.java"
EnclosingMethod: com.google.common.collect.Multimaps$MapMultimap.get:(Ljava/lang/Object;)Ljava/util/Set;
NestHost: com.google.common.collect.Multimaps
InnerClasses:
  private MapMultimap = com.google.common.collect.Multimaps$MapMultimap of com.google.common.collect.Multimaps
  com.google.common.collect.Multimaps$MapMultimap$1
  com.google.common.collect.Multimaps$MapMultimap$1$1
  abstract ImprovedAbstractSet = com.google.common.collect.Sets$ImprovedAbstractSet of com.google.common.collect.Sets