added jmath library

src/main/java/net/woggioni/jwo/Hash.java

@@ -22,6 +22,11 @@ public class Hash {
         SHA512("SHA-512");
 
         private final String key;
+
+        @SneakyThrows
+        public MessageDigest newMessageDigest() {
+            return MessageDigest.getInstance(key);
+        }
     }
 
     @Getter

src/main/java/net/woggioni/jwo/Requirement.java

@@ -0,0 +1,25 @@
+package net.woggioni.jwo;
+
+import lombok.AccessLevel;
+import lombok.RequiredArgsConstructor;
+import lombok.SneakyThrows;
+
+import java.util.function.Supplier;
+
+import static net.woggioni.jwo.JWO.newThrowable;
+
+@RequiredArgsConstructor(access = AccessLevel.PRIVATE)
+public class Requirement {
+    private final Supplier<Boolean> booleanSupplier;
+
+    public static Requirement require(Supplier<Boolean> booleanSupplier) {
+        return new Requirement(booleanSupplier);
+    }
+
+    @SneakyThrows
+    public <T extends Throwable> void otherwise(Class<T> cls, String format, Object... args) {
+        if(!booleanSupplier.get()) {
+            throw newThrowable(cls, format, args);
+        }
+    }
+}