Using constant string vector instead of irep_idt

The irep_idt class may not have been initialized when we reach this
vector declaration, which could lead to a runtime error.
Using a vector of string instead is safe.

Author: romainbrenguier

src/java_bytecode/java_bytecode_instrument.cpp

@@ -79,15 +79,12 @@ class java_bytecode_instrumentt:public messaget
   codet instrument_expr(const exprt &expr);
 };
 
-
-const std::vector<irep_idt> exception_needed_classes =
-{
+const std::vector<std::string> exception_needed_classes = { // NOLINT
   "java.lang.ArithmeticException",
   "java.lang.ArrayIndexOutOfBoundsException",
   "java.lang.ClassCastException",
   "java.lang.NegativeArraySizeException",
-  "java.lang.NullPointerException"
-};
+  "java.lang.NullPointerException"};
 
 /// Creates a class stub for exc_name and generates a
 ///  conditional GOTO such that exc_name is thrown when

src/java_bytecode/java_bytecode_instrument.h

@@ -26,6 +26,6 @@ void java_bytecode_instrument(
   const bool throw_runtime_exceptions,
   message_handlert &_message_handler);
 
-extern const std::vector<irep_idt> exception_needed_classes;
+extern const std::vector<std::string> exception_needed_classes;
 
 #endif