https://github.com/eclipse/eclipse-collections/eclipse-collections-api: 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
  • Sirisha Pratha 
public interface org.eclipse.collections.api.block.function.primitive.DoubleDoubleToDoubleFunction extends java.util.function.DoubleBinaryOperator, java.io.Serializable
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: org.eclipse.collections.api.block.function.primitive.DoubleDoubleToDoubleFunction
  super_class: java.lang.Object
{
  public abstract double valueOf(double, double);
    descriptor: (DD)D
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    MethodParameters:
       Name  Flags
      left   
      right  

  public double applyAsDouble(double, double);
    descriptor: (DD)D
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=5, args_size=3
        start local 0 // org.eclipse.collections.api.block.function.primitive.DoubleDoubleToDoubleFunction this
        start local 1 // double left
        start local 3 // double right
         0: .line 29
            aload 0 /* this */
            dload 1 /* left */
            dload 3 /* right */
            invokeinterface org.eclipse.collections.api.block.function.primitive.DoubleDoubleToDoubleFunction.valueOf:(DD)D
            dreturn
        end local 3 // double right
        end local 1 // double left
        end local 0 // org.eclipse.collections.api.block.function.primitive.DoubleDoubleToDoubleFunction this
      LocalVariableTable:
        Start  End  Slot   Name  Signature
            0    1     0   this  Lorg/eclipse/collections/api/block/function/primitive/DoubleDoubleToDoubleFunction;
            0    1     1   left  D
            0    1     3  right  D
    MethodParameters:
       Name  Flags
      left   
      right  
}
SourceFile: "DoubleDoubleToDoubleFunction.java"
    RuntimeVisibleAnnotations: 
      java.lang.FunctionalInterface()