Enhancement: Allowing zero length in static array

.test-env

@@ -1,6 +1,6 @@
 # Configs for testing repo download:
 SDK_TESTING_URL="https://github.com/algorand/algorand-sdk-testing"
-SDK_TESTING_BRANCH="master"
+SDK_TESTING_BRANCH="zero-length"
 SDK_TESTING_HARNESS="test-harness"
 
 INSTALL_ONLY=0

src/main/java/com/algorand/algosdk/abi/ABIType.java

@@ -9,7 +9,7 @@
 
 public abstract class ABIType {
     public static final int ABI_DYNAMIC_HEAD_BYTE_LEN = 2;
-    private static final Pattern staticArrayPattern = Pattern.compile("^(?<elemT>[a-z\\d\\[\\](),]+)\\[(?<len>[1-9][\\d]*)]$");
+    private static final Pattern staticArrayPattern = Pattern.compile("^(?<elemT>[a-z\\d\\[\\](),]+)\\[(?<len>0|[1-9][\\d]*)]$");
     private static final Pattern ufixedPattern = Pattern.compile("^ufixed(?<size>[1-9][\\d]*)x(?<precision>[1-9][\\d]*)$");
 
     /**

src/main/java/com/algorand/algosdk/abi/TypeArrayStatic.java

@@ -7,8 +7,8 @@ public class TypeArrayStatic extends ABIType {
     public final int length;
 
     public TypeArrayStatic(ABIType elemType, int length) {
-        if (length < 1)
-            throw new IllegalArgumentException("static-array initialize failure: array length should be at least 1");
+        if (length < 0)
+            throw new IllegalArgumentException("static-array initialize failure: array length should be non-negative");
         this.elemType = elemType;
         this.length = length;
     }

src/test/java/com/algorand/algosdk/abi/TestTypes.java

@@ -314,7 +314,7 @@ public void TestTypeFromStringInvalid() {
                 "[][][]",
                 "stuff[]",
                 // static array
-                "ufixed32x10[0]",
+                "bool[01]",
                 "byte[10 ]",
                 "uint64[0x21]",
                 // tuple