NoIssue: Add first sendCommand() method

src/main/java/com/r35157/driver/ledsign/LedSign.java

@@ -0,0 +1,7 @@
+package com.r35157.driver.ledsign;
+
+import org.jetbrains.annotations.NotNull;
+
+public interface LedSign {
+    void sendCommand(@NotNull byte[] payload);
+}

src/main/java/com/r35157/driver/ledsign/SomeInterface.java

@@ -1,6 +0,0 @@
-package com.r35157.driver.ledsign;
-
-public interface SomeInterface {
-    String concat(String x, String y);
-    void divideByZero() throws ArithmeticException;
-}