allow to figure out, whether the Point.Builder has any fields

since the build mehtod contains validation for fields emptiness, there should be also way, how to figure out, whether the Builder contains any fields (to prevent the build method from throwing an exception)

src/main/java/org/influxdb/dto/Point.java

@@ -187,6 +187,15 @@ public Builder time(final long timeToSet, final TimeUnit precisionToSet) {
       return this;
     }
 
+    /**
+     * Does this builder contain any fields?
+     *
+     * @return true, if the builder contains any fields, false otherwise.
+     */
+    public boolean hasFields() {
+      return !fields.isEmpty();
+    }
+
     /**
      * Create a new Point.
      *

src/test/java/org/influxdb/dto/PointTest.java

@@ -330,4 +330,13 @@ public void testUnEquals() throws Exception {
 		// THEN equals returns true
 		assertThat(equals).isEqualTo(false);
 	}
+
+	@Test
+	public void testBuilderHasFields() {
+		Point.Builder pointBuilder = Point.measurement("nulltest").time(1, TimeUnit.NANOSECONDS).tag("foo", "bar");
+		assertThat(pointBuilder.hasFields()).isFalse();
+
+		pointBuilder.addField("testfield", 256);
+		assertThat(pointBuilder.hasFields()).isTrue();
+	}
 }