adding new module

spring-5-reactive/src/main/java/com/baeldung/jupiter/MethodParameterFactory.java

@@ -0,0 +1,46 @@
+package com.baeldung.jupiter;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.core.annotation.SynthesizingMethodParameter;
+import org.springframework.util.Assert;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Executable;
+import java.lang.reflect.Method;
+import java.lang.reflect.Parameter;
+
+abstract class MethodParameterFactory {
+
+    private MethodParameterFactory() {
+    }
+
+    public static MethodParameter createMethodParameter(Parameter parameter) {
+        Assert.notNull(parameter, "Parameter must not be null");
+        Executable executable = parameter.getDeclaringExecutable();
+        if (executable instanceof Method) {
+            return new MethodParameter((Method) executable, getIndex(parameter));
+        }
+        return new MethodParameter((Constructor<?>) executable, getIndex(parameter));
+    }
+
+    public static SynthesizingMethodParameter createSynthesizingMethodParameter(Parameter parameter) {
+        Assert.notNull(parameter, "Parameter must not be null");
+        Executable executable = parameter.getDeclaringExecutable();
+        if (executable instanceof Method) {
+            return new SynthesizingMethodParameter((Method) executable, getIndex(parameter));
+        }
+        throw new UnsupportedOperationException("Cannot create a SynthesizingMethodParameter for a constructor parameter: " + parameter);
+    }
+
+    private static int getIndex(Parameter parameter) {
+        Assert.notNull(parameter, "Parameter must not be null");
+        Executable executable = parameter.getDeclaringExecutable();
+        Parameter[] parameters = executable.getParameters();
+        for (int i = 0; i < parameters.length; i++) {
+            if (parameters[i] == parameter) {
+                return i;
+            }
+        }
+        throw new IllegalStateException(String.format("Failed to resolve index of parameter [%s] in executable [%s]", parameter, executable.toGenericString()));
+    }
+}