[fix][misc] Preserve the sign of negative fractions in text output

pulsar-broker/src/test/java/org/apache/pulsar/utils/SimpleTextOutputStreamTest.java

@@ -24,6 +24,7 @@
 import java.nio.charset.StandardCharsets;
 import org.apache.pulsar.common.util.SimpleTextOutputStream;
 import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;
 
 @Test(groups = "utils")
@@ -104,6 +105,28 @@ public void testDoubleFormat() {
         assertEquals(str(), "-123456.100");
     }
 
+    @DataProvider
+    public Object[][] fractionalValues() {
+        return new Object[][] {
+            {-0.5, "-0.500"},
+            {-0.05, "-0.050"},
+            {-0.005, "-0.005"},
+            {-0.0005, "-0.0"},
+            {0.5, "0.500"},
+            {0.0005, "0.0"}
+        };
+    }
+
+    @Test(dataProvider = "fractionalValues")
+    public void testFractionalDoubleFormat(double value, String expected) {
+        try {
+            stream.write(value);
+            assertEquals(buf.toString(StandardCharsets.UTF_8), expected);
+        } finally {
+            buf.release();
+        }
+    }
+
     @Test
     public void testString() {
         stream.writeEncoded("�\b`~�ýý8ýH\\abcd\"");

pulsar-common/src/main/java/org/apache/pulsar/common/util/SimpleTextOutputStream.java

@@ -125,6 +125,9 @@ public SimpleTextOutputStream write(long n) {
 
     public SimpleTextOutputStream write(double d) {
         long i = (long) d;
+        if (d < 0 && i == 0) {
+            write('-');
+        }
         write(i);
 
         long r = Math.abs((long) (1000 * (d - i)));