Turn some .i files into .swig

This helps with the import / export process.

ortools/algorithms/java/BUILD.bazel

@@ -17,7 +17,7 @@ load("//bazel:swig_java.bzl", "ortools_java_wrap_cc")
 
 ortools_java_wrap_cc(
     name = "knapsacksolver",
-    src = "knapsack_solver.i",
+    src = "knapsack_solver.swig",
     module = "operations_research_algorithms",
     package = "com.google.ortools.algorithms",
     swig_includes = [

ortools/algorithms/java/CMakeLists.txt

@@ -11,17 +11,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-set_property(SOURCE knapsack_solver.i PROPERTY CPLUSPLUS ON)
-set_property(SOURCE knapsack_solver.i PROPERTY SWIG_MODULE_NAME main)
-set_property(SOURCE knapsack_solver.i PROPERTY COMPILE_DEFINITIONS
+set_property(SOURCE knapsack_solver.swig PROPERTY CPLUSPLUS ON)
+set_property(SOURCE knapsack_solver.swig PROPERTY SWIG_MODULE_NAME main)
+set_property(SOURCE knapsack_solver.swig PROPERTY COMPILE_DEFINITIONS
   ${OR_TOOLS_COMPILE_DEFINITIONS} ABSL_MUST_USE_RESULT=)
-set_property(SOURCE knapsack_solver.i PROPERTY COMPILE_OPTIONS
+set_property(SOURCE knapsack_solver.swig PROPERTY COMPILE_OPTIONS
   -package ${JAVA_PACKAGE}.algorithms)
 swig_add_library(jnialgorithms
   TYPE OBJECT
   LANGUAGE java
   OUTPUT_DIR ${JAVA_PROJECT_DIR}/${JAVA_SRC_PATH}/algorithms
-  SOURCES knapsack_solver.i)
+  SOURCES knapsack_solver.swig)
 
 target_include_directories(jnialgorithms PRIVATE ${JNI_INCLUDE_DIRS})
 set_target_properties(jnialgorithms PROPERTIES

ortools/algorithms/java/knapsack_solver.swig

@@ -21,7 +21,7 @@
 %include "enums.swg"
 
 %include "ortools/base/base.i"
-%import "ortools/util/java/vector.i"
+%import "ortools/util/java/vector.swig"
 
 %{
 #include "ortools/algorithms/knapsack_solver.h"