In Java bindings, wrap version constants into functions to prevent inlining.

Java inlines static finals if they're defined with a constant expression. In
case of version constants we don't want that to happen, since they obviously
change from version to version. If the user substitutes a different OpenCV
jar without recompiling, we want user code to still have relevant values for
the version constants.

This arranges that by turning constant values into function calls, which no
longer count as a constant expression.

modules/java/generator/gen_java.py

@@ -785,8 +785,20 @@ public class %(jc)s {
             version_suffix =  ''.join( (epoch, major, minor) )
             self.classes[class_name].imports.add("java.lang.String")
             self.java_code[class_name]["j_code"].write("""
-    public static final String VERSION = "%(v)s", NATIVE_LIBRARY_NAME = "opencv_java%(vs)s";
-    public static final int VERSION_EPOCH = %(ep)s, VERSION_MAJOR = %(ma)s, VERSION_MINOR = %(mi)s, VERSION_REVISION = %(re)s;
+    // these constants are wrapped inside functions to prevent inlining
+    private static String getVersion() { return "%(v)s"; }
+    private static String getNativeLibraryName() { return "opencv_java%(vs)s"; }
+    private static int getVersionEpoch() { return %(ep)s; }
+    private static int getVersionMajor() { return %(ma)s; }
+    private static int getVersionMinor() { return %(mi)s; }
+    private static int getVersionRevision() { return %(re)s; }
+
+    public static final String VERSION = getVersion();
+    public static final String NATIVE_LIBRARY_NAME = getNativeLibraryName();
+    public static final int VERSION_EPOCH = getVersionEpoch();
+    public static final int VERSION_MAJOR = getVersionMajor();
+    public static final int VERSION_MINOR = getVersionMinor();
+    public static final int VERSION_REVISION = getVersionRevision();
 """ % { 'v' : version_str, 'vs' : version_suffix, 'ep' : epoch, 'ma' : major, 'mi' : minor, 're' : revision } )