cherrypick:Bugfix/encoder row writer (#372)

Author: Nicole00

client/src/main/java/com/vesoft/nebula/encoder/NebulaCodecImpl.java

@@ -205,7 +205,7 @@ private SchemaProviderImpl genSchemaProvider(long ver, Schema schema) {
         SchemaProviderImpl schemaProvider = new SchemaProviderImpl(ver);
         for (ColumnDef col : schema.getColumns()) {
             ColumnTypeDef type = col.getType();
-            boolean nullable = col.isSetNullable();
+            boolean nullable = col.isSetNullable() && col.isNullable();
             boolean hasDefault = col.isSetDefault_value();
             int len = type.isSetType_length() ? type.getType_length() : 0;
             schemaProvider.addField(new String(col.getName()),

client/src/main/java/com/vesoft/nebula/encoder/RowWriterImpl.java

@@ -831,6 +831,7 @@ public ByteBuffer processOutOfSpace() {
                 // Set the new offset and length
                 temp.putInt(offset, 0);
                 temp.putInt(offset + Integer.BYTES, 0);
+                continue;
             } else {
                 // Out of space string
                 if (strNum >= strList.size()) {