Added Leachman method (#1270)

* Added Leachman method

* file added

* Added test and defined methods in phase

* Deleted file

src/main/java/neqsim/thermo/phase/Phase.java

@@ -2228,6 +2228,50 @@ public double[] getProperties_GERG2008() {
     return test.propertiesGERG();
   }
 
+  /** {@inheritDoc} */
+  @Override
+  public double getDensity_Leachman(String hydrogenType) {
+    neqsim.thermo.util.Leachman.NeqSimLeachman test = 
+      new neqsim.thermo.util.Leachman.NeqSimLeachman(this, hydrogenType);
+    return test.getDensity();
+  }
+
+  /**
+   * Gets the density using the default hydrogen type ('normal').
+   * This method prints a warning if no hydrogen type is specified.
+   *
+   * @return the density calculated with the 'normal' hydrogen type.
+   */
+  public double getDensity_Leachman() {
+    // Warn the user that no hydrogen type was specified and use "normal" by default
+    System.out.println("No hydrogen type specified. Using default type: 'normal'.");
+    return getDensity_Leachman("normal");
+  }
+
+
+
+  /** {@inheritDoc} */
+  @Override
+  public double[] getProperties_Leachman(String hydrogenType) {
+    neqsim.thermo.util.Leachman.NeqSimLeachman test = 
+      new neqsim.thermo.util.Leachman.NeqSimLeachman(this, hydrogenType);      
+    return test.propertiesLeachman();
+  }
+
+
+  /**
+ * Gets the Leachman properties of a phase using the default hydrogen type ('normal').
+ * This method prints a warning if no hydrogen type is specified.
+ *
+ * @return an array of properties of type double.
+ */
+  public double[] getProperties_Leachman() {
+    // Warn the user and use the default hydrogen type
+    System.out.println("No hydrogen type specified. Using default type: 'normal'.");
+    return getProperties_Leachman("normal");
+  }
+
+
   /** {@inheritDoc} */
   @Override
   public double getDensity_AGA8() {

src/main/java/neqsim/thermo/phase/PhaseInterface.java

@@ -419,6 +419,39 @@ public default void initPhysicalProperties(String name) {
    */
   public double[] getProperties_GERG2008();
 
+
+  /**
+   * method to get Leachman density of a phase using the Leachman EoS.
+   *
+   * @return density with unit kg/m3
+   */
+  public double getDensity_Leachman(String hydrogenType);
+
+  /**
+    * Overloaded method to get the Leachman density with default hydrogen type ('normal').
+    *
+    * @return density with unit kg/m3
+    */
+  public double getDensity_Leachman();
+
+  /**
+   * <p>
+   * method to get Leachman properties of a phase using the Leachman EoS.
+   * </p>
+   *
+   * @return an array of type double
+   */
+
+  public double[] getProperties_Leachman(String hydrogenType);
+
+  /**
+    * Overloaded method to get the Leachman properties with default hydrogen type ('normal').
+    *
+    * @return density with unit kg/m3
+    */
+
+  public double[] getProperties_Leachman();
+
   /**
    * method to get density of a phase note: does not use Peneloux volume correction.
    *