OracleConnection may leak if handler is null

Do not connect if handler is null Signed-off-by: Thomas Segismont <tsegismont@gmail.com>

Author: tsegismont

vertx-oracle-client/src/main/asciidoc/index.adoc

@@ -6,7 +6,17 @@ scalability and low overhead.
 
 *Features*
 
-* todo
+* Event driven
+* Java 8 Date and Time
+
+*Not supported yet*
+
+* Built-in connection pooling
+* RxJava API
+* Prepared queries caching
+* Cursor
+* Row streaming
+* Stored Procedures
 
 WARNING: this module is in tech preview
 
@@ -144,6 +154,19 @@ include::transactions.adoc[]
 
 include::cursor.adoc[]
 
+== Data types supported
+
+Currently, the client supports the following Oracle data types:
+
+* CHAR/VARCHAR2(`java.lang.String`)
+* NCHAR/NVARCHAR2(`java.lang.String`)
+* NUMBER(`{@link java.math.BigDecimal}`)
+* FLOAT(`java.lang.Double`)
+* DATE(`java.time.LocalDate`)
+* TIMESTAMP(`java.time.LocalDateTime`)
+
+Tuple decoding uses the above types when storing values.
+
 == Tracing queries
 
 include::tracing.adoc[]