make API backward-compatible.

Author: kfriedberger

src/org/sosy_lab/java_smt/api/FloatingPointFormulaManager.java

@@ -8,6 +8,7 @@
 
 package org.sosy_lab.java_smt.api;
 
+import static org.sosy_lab.java_smt.api.FormulaManager.API_METHOD_NOT_IMPLEMENTED;
 import static org.sosy_lab.java_smt.api.FormulaType.getFloatingPointType;
 
 import java.math.BigDecimal;
@@ -41,8 +42,10 @@ public interface FloatingPointFormulaManager {
    * Converts a rounding mode formula to the corresponding enum value. This method is the inverse of
    * {@link #makeRoundingMode(FloatingPointRoundingMode)}.
    */
-  FloatingPointRoundingMode fromRoundingModeFormula(
-      FloatingPointRoundingModeFormula pRoundingModeFormula);
+  default FloatingPointRoundingMode fromRoundingModeFormula(
+      FloatingPointRoundingModeFormula pRoundingModeFormula) {
+    throw new UnsupportedOperationException(API_METHOD_NOT_IMPLEMENTED);
+  }
 
   /**
    * Creates a floating point formula representing the given double value with the specified type.

src/org/sosy_lab/java_smt/api/FormulaManager.java

@@ -20,6 +20,16 @@
 /** FormulaManager class contains all operations which can be performed on formulas. */
 public interface FormulaManager {
 
+  /**
+   * Standardized message for not implemented API methods.
+   *
+   * <p>This constant can be used in {@link UnsupportedOperationException} to indicate that a
+   * certain method is not implemented by some subclass. We recommend using this constant in API
+   * extensions where the default implementation throws an exception.
+   */
+  String API_METHOD_NOT_IMPLEMENTED =
+      "The requested method is not implemented in the current implementation of this interface.";
+
   /**
    * Returns the Integer-Theory. Because most SAT-solvers support automatic casting between Integer-
    * and Rational-Theory, the Integer- and the RationalFormulaManager both return the same Formulas