https://github.com/eclipse/eclipse-collections/eclipse-collections: Eclipse Collections is a collections framework for Java. It has JDK-compatible List, Set and Map implementations with a rich API and set of utility classes that work with any JDK compatible Collections, Arrays, Maps or Strings. The iteration protocol was inspired by the Smalltalk collection framework.
  • Craig P. Motlin
  • Donald Raab
  • Mohammad A. Rezaei
  • Hiroshi Ito
  • Nikhil J. Nanivadekar 
final class org.eclipse.collections.impl.block.factory.Functions0$NullFunction<T> implements org.eclipse.collections.api.block.function.Function0<T>
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: org.eclipse.collections.impl.block.factory.Functions0$NullFunction
  super_class: java.lang.Object
{
  private static final long serialVersionUID;
    descriptor: J
    flags: (0x001a) ACC_PRIVATE, ACC_STATIC, ACC_FINAL
    ConstantValue: 1

  private void <init>();
    descriptor: ()V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.eclipse.collections.impl.block.factory.Functions0$NullFunction this
         0: .line 208
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // org.eclipse.collections.impl.block.factory.Functions0$NullFunction this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/eclipse/collections/impl/block/factory/Functions0$NullFunction<TT;>;

  public T value();
    descriptor: ()Ljava/lang/Object;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.eclipse.collections.impl.block.factory.Functions0$NullFunction this
         0: .line 215
            aconst_null
            areturn
        end local 0 // org.eclipse.collections.impl.block.factory.Functions0$NullFunction this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/eclipse/collections/impl/block/factory/Functions0$NullFunction<TT;>;
    Signature: ()TT;
}
Signature: <T:Ljava/lang/Object;>Ljava/lang/Object;Lorg/eclipse/collections/api/block/function/Function0<TT;>;
SourceFile: "Functions0.java"
NestHost: org.eclipse.collections.impl.block.factory.Functions0
InnerClasses:
  private final NullFunction = org.eclipse.collections.impl.block.factory.Functions0$NullFunction of org.eclipse.collections.impl.block.factory.Functions0