Expose a way for derived languages to specify additional entry points

Lazy methods can be extened to load additional methods as entry points.
This allows this to be meaningfully used by subclasses of
java_bytecode_language

Author: thk123

jbmc/src/java_bytecode/java_bytecode_language.cpp

@@ -123,6 +123,9 @@ void java_bytecode_languaget::get_language_options(const cmdlinet &cmd)
     extra_entry_points.end(),
     std::back_inserter(extra_methods),
     build_load_method_by_regex);
+  const auto &new_points = build_extra_entry_points(cmd);
+  extra_methods.insert(
+    extra_methods.end(), new_points.begin(), new_points.end());
 
   if(cmd.isset("java-cp-include-files"))
   {
@@ -1207,3 +1210,13 @@ bool java_bytecode_languaget::to_expr(
 java_bytecode_languaget::~java_bytecode_languaget()
 {
 }
+
+/// This method should be overloaded to provide alternative approaches for
+/// specifying extra entry points. To provide a regex entry point, the command
+/// line option `--lazy-methods-extra-entry-point` can be used directly.
+std::vector<load_extra_methodst>
+java_bytecode_languaget::build_extra_entry_points(
+  const cmdlinet &command_line) const
+{
+  return {};
+}

jbmc/src/java_bytecode/java_bytecode_language.h

@@ -199,6 +199,8 @@ class java_bytecode_languaget:public languaget
   std::vector<irep_idt> java_load_classes;
 
 private:
+  virtual std::vector<load_extra_methodst>
+  build_extra_entry_points(const cmdlinet &command_line) const;
   const std::unique_ptr<const select_pointer_typet> pointer_type_selector;
 
   /// Maps synthetic method names on to the particular type of synthetic method