diff --git a/optaplanner-core/src/main/java/org/optaplanner/core/api/solver/Solver.java b/optaplanner-core/src/main/java/org/optaplanner/core/api/solver/Solver.java
index e381103bdf..77d61ce9c7 100644
--- a/optaplanner-core/src/main/java/org/optaplanner/core/api/solver/Solver.java
+++ b/optaplanner-core/src/main/java/org/optaplanner/core/api/solver/Solver.java
@@ -84,18 +84,13 @@ public interface Solver<Solution_> {
     Solution_ solve(Solution_ planningProblem);
 
     /**
-     * Solves the planning problem and returns the best solution encountered
-     * (which might or might not be optimal, feasible or even initialized).
-     * <p>
-     * It can take seconds, minutes, even hours or days before this method returns,
-     * depending on the {@link Termination} configuration.
-     * To terminate a {@link Solver} early, call {@link #terminateEarly()}.
-     * @param planningProblem never null, usually its planning variables are uninitialized
-     * @return never null, but it can return the original, uninitialized {@link PlanningSolution} with a {@link Score} null.
-     * @see #terminateEarly()
+     * Retained for backwards compatibility with 6.x. This method will be removed in 8.0.
+     * @param planningProblem never null
+     * @return never null
+     * @deprecated In favor of {@link #solve(Object)}
      */
     @Deprecated
-    Solution_ solve(Solution planningProblem);
+    Solution solve(Solution planningProblem);
 
     /**
      * This method is thread-safe.
diff --git a/optaplanner-core/src/main/java/org/optaplanner/core/impl/solver/DefaultSolver.java b/optaplanner-core/src/main/java/org/optaplanner/core/impl/solver/DefaultSolver.java
index 0f86721f06..6adefb2b8c 100644
--- a/optaplanner-core/src/main/java/org/optaplanner/core/impl/solver/DefaultSolver.java
+++ b/optaplanner-core/src/main/java/org/optaplanner/core/impl/solver/DefaultSolver.java
@@ -187,13 +187,8 @@ public final Solution_ solve(Solution_ planningProblem) {
         return solverScope.getBestSolution();
     }
 
-    public Solution_ solve(Solution planningProblem) {
-        if (planningProblem == null) {
-            throw new IllegalArgumentException("The planningProblem (" + planningProblem
-                    + ") must not be null.");
-        }
-        // we can do this, since this legacy Solution is in fact the same type as Solution_
-        return solve((Solution_)planningProblem);
+    public Solution solve(Solution planningProblem) {
+        return (Solution) solve((Solution_) planningProblem);
     }
 
     public void outerSolvingStarted(DefaultSolverScope<Solution_> solverScope) {