https://github.com/oracle/graal: GraalVM is an ecosystem for compiling and running applications written in multiple languages. GraalVM removes the isolation between programming languages and enables interoperability in a shared runtime. 
public final class org.graalvm.options.OptionMap<T>
  minor version: 0
  major version: 59
  flags: flags: (0x0031) ACC_PUBLIC, ACC_FINAL, ACC_SUPER
  this_class: org.graalvm.options.OptionMap
  super_class: java.lang.Object
{
  private static final org.graalvm.options.OptionMap<?> EMPTY;
    descriptor: Lorg/graalvm/options/OptionMap;
    flags: (0x001a) ACC_PRIVATE, ACC_STATIC, ACC_FINAL
    Signature: Lorg/graalvm/options/OptionMap<*>;

  final java.util.Map<java.lang.String, T> backingMap;
    descriptor: Ljava/util/Map;
    flags: (0x0010) ACC_FINAL
    Signature: Ljava/util/Map<Ljava/lang/String;TT;>;

  final java.util.Map<java.lang.String, T> readonlyMap;
    descriptor: Ljava/util/Map;
    flags: (0x0010) ACC_FINAL
    Signature: Ljava/util/Map<Ljava/lang/String;TT;>;

  static void <clinit>();
    descriptor: ()V
    flags: (0x0008) ACC_STATIC
    Code:
      stack=3, locals=0, args_size=0
         0: .line 58
            new org.graalvm.options.OptionMap
            dup
            invokestatic java.util.Collections.emptyMap:()Ljava/util/Map;
            invokespecial org.graalvm.options.OptionMap.<init>:(Ljava/util/Map;)V
            putstatic org.graalvm.options.OptionMap.EMPTY:Lorg/graalvm/options/OptionMap;
            return
      LocalVariableTable:
        Start  End  Slot  Name  Signature

  void <init>(java.util.Map<java.lang.String, T>);
    descriptor: (Ljava/util/Map;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // org.graalvm.options.OptionMap this
        start local 1 // java.util.Map map
         0: .line 63
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 64
            aload 0 /* this */
            aload 1 /* map */
            putfield org.graalvm.options.OptionMap.backingMap:Ljava/util/Map;
         2: .line 65
            aload 0 /* this */
            aload 1 /* map */
            invokestatic java.util.Collections.unmodifiableMap:(Ljava/util/Map;)Ljava/util/Map;
            putfield org.graalvm.options.OptionMap.readonlyMap:Ljava/util/Map;
         3: .line 66
            return
        end local 1 // java.util.Map map
        end local 0 // org.graalvm.options.OptionMap this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    4     0  this  Lorg/graalvm/options/OptionMap<TT;>;
            0    4     1   map  Ljava/util/Map<Ljava/lang/String;TT;>;
    Signature: (Ljava/util/Map<Ljava/lang/String;TT;>;)V
    MethodParameters:
      Name  Flags
      map   

  public static <T> org.graalvm.options.OptionMap<T> empty();
    descriptor: ()Lorg/graalvm/options/OptionMap;
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=1, locals=0, args_size=0
         0: .line 77
            getstatic org.graalvm.options.OptionMap.EMPTY:Lorg/graalvm/options/OptionMap;
            areturn
      LocalVariableTable:
        Start  End  Slot  Name  Signature
    Signature: <T:Ljava/lang/Object;>()Lorg/graalvm/options/OptionMap<TT;>;

  public T get(java.lang.String);
    descriptor: (Ljava/lang/String;)Ljava/lang/Object;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // org.graalvm.options.OptionMap this
        start local 1 // java.lang.String key
         0: .line 91
            aload 0 /* this */
            getfield org.graalvm.options.OptionMap.readonlyMap:Ljava/util/Map;
            aload 1 /* key */
            invokeinterface java.util.Map.get:(Ljava/lang/Object;)Ljava/lang/Object;
            areturn
        end local 1 // java.lang.String key
        end local 0 // org.graalvm.options.OptionMap this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/graalvm/options/OptionMap<TT;>;
            0    1     1   key  Ljava/lang/String;
    Signature: (Ljava/lang/String;)TT;
    MethodParameters:
      Name  Flags
      key   

  public java.util.Set<java.util.Map$Entry<java.lang.String, T>> entrySet();
    descriptor: ()Ljava/util/Set;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.graalvm.options.OptionMap this
         0: .line 102
            aload 0 /* this */
            getfield org.graalvm.options.OptionMap.readonlyMap:Ljava/util/Map;
            invokeinterface java.util.Map.entrySet:()Ljava/util/Set;
            areturn
        end local 0 // org.graalvm.options.OptionMap this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/graalvm/options/OptionMap<TT;>;
    Signature: ()Ljava/util/Set<Ljava/util/Map$Entry<Ljava/lang/String;TT;>;>;

  public int hashCode();
    descriptor: ()I
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.graalvm.options.OptionMap this
         0: .line 110
            aload 0 /* this */
            getfield org.graalvm.options.OptionMap.readonlyMap:Ljava/util/Map;
            invokeinterface java.util.Map.hashCode:()I
            ireturn
        end local 0 // org.graalvm.options.OptionMap this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/graalvm/options/OptionMap<TT;>;

  public boolean equals(java.lang.Object);
    descriptor: (Ljava/lang/Object;)Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // org.graalvm.options.OptionMap this
        start local 1 // java.lang.Object obj
         0: .line 119
            aload 1 /* obj */
            instanceof org.graalvm.options.OptionMap
            ifeq 2
         1: .line 120
            aload 0 /* this */
            getfield org.graalvm.options.OptionMap.readonlyMap:Ljava/util/Map;
            aload 1 /* obj */
            checkcast org.graalvm.options.OptionMap
            getfield org.graalvm.options.OptionMap.readonlyMap:Ljava/util/Map;
            invokeinterface java.util.Map.equals:(Ljava/lang/Object;)Z
            ireturn
         2: .line 122
      StackMap locals:
      StackMap stack:
            iconst_0
            ireturn
        end local 1 // java.lang.Object obj
        end local 0 // org.graalvm.options.OptionMap this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    3     0  this  Lorg/graalvm/options/OptionMap<TT;>;
            0    3     1   obj  Ljava/lang/Object;
    MethodParameters:
      Name  Flags
      obj   
}
Signature: <T:Ljava/lang/Object;>Ljava/lang/Object;
SourceFile: "OptionMap.java"
InnerClasses:
  public abstract Entry = java.util.Map$Entry of java.util.Map