chore: replace use of string.join for android 21 (#111)

* chore: replace ust of string.join for java6 back-compat
* move eppo value test class and fix delimiter
* patch bump

Author: typotter

build.gradle

@@ -6,7 +6,7 @@ plugins {
 }
 
 group = 'cloud.eppo'
-version = '3.10.1-SNAPSHOT'
+version = '3.10.1'
 ext.isReleaseVersion = !version.endsWith("SNAPSHOT")
 
 java {

src/main/java/cloud/eppo/api/EppoValue.java

@@ -1,6 +1,7 @@
 package cloud.eppo.api;
 
 import cloud.eppo.ufc.dto.EppoValueType;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Objects;
 
@@ -101,7 +102,8 @@ public String toString() {
       case STRING:
         return this.stringValue;
       case ARRAY_OF_STRING:
-        return String.join(" ,", this.stringArrayValue);
+        // Android21 back-compatability
+        return joinStringArray(this.stringArrayValue);
       case NULL:
         return "";
       default:
@@ -130,4 +132,21 @@ public boolean equals(Object otherObject) {
   public int hashCode() {
     return Objects.hash(type, boolValue, doubleValue, stringValue, stringArrayValue);
   }
+
+  /** This method is to allow for Android 21 support; String.join was introduced in API 26 */
+  private static String joinStringArray(List<String> stringArray) {
+    if (stringArray == null || stringArray.isEmpty()) {
+      return "";
+    }
+    String delimiter = ", ";
+    StringBuilder stringBuilder = new StringBuilder();
+    Iterator<String> iterator = stringArray.iterator();
+    while (iterator.hasNext()) {
+      stringBuilder.append(iterator.next());
+      if (iterator.hasNext()) {
+        stringBuilder.append(delimiter);
+      }
+    }
+    return stringBuilder.toString();
+  }
 }

src/test/java/cloud/eppo/EppoValueTest.java

@@ -0,0 +1,68 @@
+package cloud.eppo.api;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+public class EppoValueTest {
+  @Test
+  public void testDoubleValue() {
+    EppoValue eppoValue = EppoValue.valueOf(123.4567);
+    assertEquals(123.4567, eppoValue.doubleValue(), 0.0);
+  }
+
+  @Test
+  public void testToStringWithStringArray() {
+    // Test with multiple values
+    List<String> values = Arrays.asList("one", "two", "three");
+    EppoValue value = EppoValue.valueOf(values);
+    assertEquals("one, two, three", value.toString());
+
+    // Test with single value
+    List<String> singleValue = Arrays.asList("solo");
+    EppoValue singleValueObj = EppoValue.valueOf(singleValue);
+    assertEquals("solo", singleValueObj.toString());
+
+    // Test with empty list
+    List<String> emptyList = new ArrayList<>();
+    EppoValue emptyValue = EppoValue.valueOf(emptyList);
+    assertEquals("", emptyValue.toString());
+  }
+
+  @Test
+  public void testStringArrayJoining() {
+    // Test joining behavior with various arrays
+    List<String> values = Arrays.asList("a", "b", "c");
+    EppoValue value = EppoValue.valueOf(values);
+    assertEquals("a, b, c", value.toString());
+
+    // Test with values containing the delimiter
+    List<String> commaValues = Arrays.asList("first,item", "second ,item");
+    EppoValue commaValue = EppoValue.valueOf(commaValues);
+    assertEquals("first,item, second ,item", commaValue.toString());
+  }
+
+  @Test
+  public void testToStringConsistencyAcrossTypes() {
+    // Verify string representation is consistent across types
+    EppoValue boolValue = EppoValue.valueOf(true);
+    assertEquals("true", boolValue.toString());
+
+    EppoValue numValue = EppoValue.valueOf(42.5);
+    assertEquals("42.5", numValue.toString());
+
+    EppoValue strValue = EppoValue.valueOf("test");
+    assertEquals("test", strValue.toString());
+
+    EppoValue nullValue = EppoValue.nullValue();
+    assertEquals("", nullValue.toString());
+
+    // String array should now use our custom joiner
+    List<String> array = Arrays.asList("test1", "test2");
+    EppoValue arrayValue = EppoValue.valueOf(array);
+    assertEquals("test1, test2", arrayValue.toString());
+  }
+}