reintroduced modifiers needed for serialization.

src/main/java/org/apache/commons/math3/ode/nonstiff/ClassicalRungeKuttaStepInterpolator.java

@@ -68,7 +68,7 @@ class ClassicalRungeKuttaStepInterpolator
      * interpolators by cloning an uninitialized model and latter initializing
      * the copy.
      */
-    ClassicalRungeKuttaStepInterpolator() {
+    public ClassicalRungeKuttaStepInterpolator() {
     }
 
     /** Copy constructor.

src/main/java/org/apache/commons/math3/ode/nonstiff/DormandPrince54StepInterpolator.java

@@ -97,7 +97,7 @@ class DormandPrince54StepInterpolator
    * prototyping design pattern to create the step interpolators by
    * cloning an uninitialized model and latter initializing the copy.
    */
-  DormandPrince54StepInterpolator() {
+  public DormandPrince54StepInterpolator() {
     super();
     v1 = null;
     v2 = null;

src/main/java/org/apache/commons/math3/ode/nonstiff/DormandPrince853StepInterpolator.java

@@ -227,7 +227,7 @@ class DormandPrince853StepInterpolator
    * prototyping design pattern to create the step interpolators by
    * cloning an uninitialized model and latter initializing the copy.
    */
-  DormandPrince853StepInterpolator() {
+  public DormandPrince853StepInterpolator() {
     super();
     yDotKLast = null;
     v         = null;

src/main/java/org/apache/commons/math3/ode/nonstiff/EulerStepInterpolator.java

@@ -59,7 +59,7 @@ class EulerStepInterpolator
    * to create the step interpolators by cloning an uninitialized model
    * and later initializing the copy.
    */
-  EulerStepInterpolator() {
+  public EulerStepInterpolator() {
   }
 
   /** Copy constructor.

src/main/java/org/apache/commons/math3/ode/nonstiff/GillStepInterpolator.java

@@ -75,7 +75,7 @@ class GillStepInterpolator
    * to create the step interpolators by cloning an uninitialized model
    * and later initializing the copy.
    */
-  GillStepInterpolator() {
+  public GillStepInterpolator() {
   }
 
   /** Copy constructor.

src/main/java/org/apache/commons/math3/ode/nonstiff/GraggBulirschStoerStepInterpolator.java

@@ -107,7 +107,7 @@ class GraggBulirschStoerStepInterpolator
    * This constructor should not be used directly, it is only intended
    * for the serialization process.
    */
-  GraggBulirschStoerStepInterpolator() {
+  public GraggBulirschStoerStepInterpolator() {
     y0Dot    = null;
     y1       = null;
     y1Dot    = null;

src/main/java/org/apache/commons/math3/ode/nonstiff/HighamHall54StepInterpolator.java

@@ -45,7 +45,7 @@ class HighamHall54StepInterpolator
    * to create the step interpolators by cloning an uninitialized model
    * and later initializing the copy.
    */
-  HighamHall54StepInterpolator() {
+  public HighamHall54StepInterpolator() {
     super();
   }
 

src/main/java/org/apache/commons/math3/ode/nonstiff/LutherStepInterpolator.java

@@ -51,7 +51,7 @@ class LutherStepInterpolator extends RungeKuttaStepInterpolator {
      * to create the step interpolators by cloning an uninitialized model
      * and later initializing the copy.
      */
-    LutherStepInterpolator() {
+    public LutherStepInterpolator() {
     }
 
     /** Copy constructor.

src/main/java/org/apache/commons/math3/ode/nonstiff/MidpointStepInterpolator.java

@@ -61,7 +61,7 @@ class MidpointStepInterpolator
    * to create the step interpolators by cloning an uninitialized model
    * and later initializing the copy.
    */
-  MidpointStepInterpolator() {
+  public MidpointStepInterpolator() {
   }
 
   /** Copy constructor.

src/main/java/org/apache/commons/math3/ode/nonstiff/ThreeEighthesStepInterpolator.java

@@ -71,7 +71,7 @@ class ThreeEighthesStepInterpolator
    * to create the step interpolators by cloning an uninitialized model
    * and later initializing the copy.
    */
-  ThreeEighthesStepInterpolator() {
+  public ThreeEighthesStepInterpolator() {
   }
 
   /** Copy constructor.